GPF Back Exhaust System (RPM Performance)

[Cholmondeley-Biscuitt]

Took the plunge and have ordered the GPF Back system (with Valve fitting and gloss CF exhaust tips), from RPM Performance. I'll also be pairing their 200CEL Sports Cat with my already fitted modified Flexi and resonated GPF Delete, along with their more robust valve spring. I'm certain the neighbours will love it too.. (images not to scale)

 

[telelaci]

I've ordered the same except the 200CEL downpipe. What ETA did you get ?
Will you change it back before every MOT test ?

 

[Cholmondeley-Biscuitt]

I've ordered the same except the 200CEL downpipe. What ETA did you get ?
Will you change it back before every MOT test ?

A couple of weeks on the delivery. As for removing it - no. I have a garage that's 'sympathetic' to modifications with respect to testing and it won't fail an emissions test so there is no point in the messing about.

 

[telelaci]

A couple of weeks on the delivery. As for removing it - no. I have a garage that's 'sympathetic' to modifications with respect to testing and it won't fail an emissions test so there is no point in the messing about.

OK, but actually it fails the emission test without middle GPF, it is there for reason, and half effective catalisator (the OEM one is 400CEL) doesn't help either.

 

[Cholmondeley-Biscuitt]

I don't think you get me; my garage assures me that it won't fail an emissions test if they do the MOT (wink wink)

 

[telelaci]

I don't think you get me; my garage assures me that it won't fail an emissions test if they do the MOT (wink wink)

I'm so stupid.

 

[Maverick]

 

[Cholmondeley-Biscuitt]

Ahh, the tangy smell of new stainless steel - The postman arrived yesterday with a large parcel, the contents of which I labelled up before eating the complimentary Haribo sweets (candy) in a single mouthful . Unfortunately, I have a 3 week wait before I can get it all to the garage for fitting. Not to worry, I can stroke my pipes of an evening whilst I'm waiting

[GPF-Back system with resonated mid-pipe, gloss C/F polished exhaust tips and upgraded valve spring from RPM Performances UK]


Carbon Fibre Exhaust Tip(s):

 

[telelaci]

Ahh, the tangy smell of new stainless steel - The postman arrived yesterday with a large parcel, the contents of which I labelled up before eating the complimentary Haribo sweets (candy) in a single mouthful . Unfortunately, I have a 3 week wait before I can get it all to the garage for fitting. Not to worry, I can stroke my pipes of an evening whilst I'm waiting

[GPF-Back system with 'custom' resonated mid-pipe, gloss C/F polished exhaust tips and upgraded valve spring from RPM Performances UK]
View attachment 21458

Hi Biscuit, will you attach a sound video please when it's installed.

 

[Cholmondeley-Biscuitt]

Hi Biscuit, will you attach a sound video please when it's installed.

I'll do my best ... iPhones are a bit s**t for capturing sound though..

 

[Cholmondeley-Biscuitt]

Update: That's the resonated GPF-Back system now fitted.
The garage had issues with the fitting of the upgraded Valve Spring, which wasn't seated properly and was causing a rattle like a penny in a bean can! So when I got home I contacted RPM for advice, then an hour on the freezing tarmac outside my house saw me sort it out.
The other odd rattle now comes from the valve flap just inside the pipe - when it's closed and there's pressure behind it (at idle or running), sometimes it will oscillate a little against the mating surface which causes a 'ping ping ping' sound. The flap is easily reached and a little poking into the exhaust tip and prodding at the flap will often stop it making the noise - I'm hoping that once it gets a bit of carbon around the tube and the mating surfaces get dirty that it will soften the sound further.

POSITIVE: The sound is lovely in Eco/Normal and better in Sport. Unfortunately, I just can't accelerate hard unless I'm wearing ear defenders (see below)!

Not so positive: There is a serious amount of DRONE after this upgrade! It's like a sound weapon! The air in the cabin just vibrates with this deep noise that builds as acceleration does, to a level that is physically painful to the ears and makes you feel ill .

It's been suggested by Daniel at RPM that there may now be too much flow, given that I have a 200cel Sports Cat, 3" flexi, GPF Delete (resonated) and now their full 3" back end (with resonated mid-pipe). One option might be to add another resonator on the straight pipe after the GPF delete or make the current one bigger.. I have also thought about putting the original GPF back on, which would be the cheapest way to reduce the flow rate and hopefully lower the cabin noise to pre-vomit levels...

You can get a feeling for the sound in this Dashcam footage I recorded on the day of fitting. The deep booming and buzzing isn't distortion as you might think - you can tell this from the clarity of the indicator sounds and the satnav instructions also being transmitted into the cabin - the noise you hear is like being sitting next to the bass speaker at heavy metal concert!
Warning: The below video may make your speakers vibrate with the Bass levels. Earphones are suggested.
link to dashcam footage.

 

[telelaci]

Hi Biscuit,

Thanks for the update. As you know I've ordered the same Resonated GPF-Back system as you, but I got a non-resonated one. My slightly bent long pipe has no resonator drum, it's only a simple pipe. My order acknoledment mail was:

Order No. 11674 Placed on Aug 4, 2022
Hyundai Kona N GPF Back Exhaust system
Valve option: Valved
Tips: Glossy Carbon
System Type: Resonated
Price: £1,095.00

And I got a non-resonated system. Dan said no sorry at all, he said he thought I wanted non-resonated system. That was his reaction. Something is wrong with that guy, he had no reason to think that, but he had reason to say "we are so sorry for this mistake...". And he should've fixed this mistake as fast as he could.
But. He said that if I'd would be willing to pay 20 more pounds for the shipping, he'd make me and send me the resonated long pipe. I sent him the money immediately (yes, despite of HIS fault, I'm so idiot) on Fri, Nov 11, 9:12 AM (a month ago), and since then there is no answer to my mails. And there is no resonated pipe either. I got a fake tracking number about a parcel that has never been dispatched, just like a good old AliExpress trick. Chinese merchants do that.

I'd like to sue the firm RPM Performances Ltd. , but my lawyer said that I'd need an invoice first. But I got no invoice he never sent me one. Most probably he keeps the VAT, and his firm doesn't pay taxes for the income. No invoice, no income, no taxes. Most probably I'll never get that I ordered. He doesn't care at all. I'm planning to write a mail to the British HMRC to make a complaint and to make them force him to send me an invoice. And then they will find out the other shady things that Daniel does with invoices, and taxes and VAT's. I think that would hit him harder than my lawsuit. I spent more than £1600 at the RPM-Performances and this is how I was treated. You know a customer's task is very simple, "choose what you want in the shop, order it, and pay for it !" - and this is what I did exactly. How can I make a mistake in this process ?

Regarding your system. This is a total fail. This is a sound that I couldn't accept, I couldn't live with it, not for a week or for a day. I'm not sure that you were luckier than me or not. Your situation is very similar, you spent lot of money and you got something you didn't want. What will you do now ? The ad says "All systems come with a carefully calculated Helmholtz resonator to help limit drone frequency within the cabin".
And then the reality is: you couldn't get more drone even if you wanted. It goes into your brain and resonates it. This sound has nothing to do with Dan Bushell's video, "almost like the stock" feeling. That you commented as @cholomondeleybiscuitt5042, and you had the same goal as mine, "...not noisy, a good deep rumble without the drone and bangs without the sharp snap/crackle..."

"On a positive note though, the sound is awesome in Eco/Normal..." - it's fine but I use my car in N mode always. That is why I bought a hot-hatch, that is N mode. Non-N mode => no hot-hatch just a regular car. I use the Normal mode only to warm up the oil. Then it's N. (actually maxed Custom with soft suspension).

Thank you Biscuit for the updates ! Would you please keep us informed, how did you solve the droning or maybe how you didn't. I hope you the bests, I hope he solves this problem for you. At least you are a British, not a foreigner from Europe like me. He has to treat you better, at least in theory. Although Scotland had lot of conflicts with England in the history. They beheaded Mary Stuart too. We will see.
What is the next step you agreed with Dan ?

 

[Deleted member 2480]

@RPM Performance might want to look into this..............

 

[Cholmondeley-Biscuitt]

... I got a fake tracking number about a parcel that has never been dispatched...

It could be that the tracking number has been created with the Courier (for admin reasons) but that the parcel has not yet been collected? This might indicate that your item has not departed from RPM Performance due to a manufacturing delay perhaps.

Regarding your system... This is a sound that I couldn't accept, I couldn't live with it, not for a week or for a day. .. you couldn't get more drone even if you wanted. It goes into your brain and resonates it...

I'm living with it for now but, having to avoid using N mode on an aggressive throttle otherwise it makes my brain and internal organs rattle.

Thank you Biscuit for the updates ! Would you please keep us informed, how did you solve the droning or maybe how you didn't.

The first stage of my experiment is to refit the original GPF, which is obviously more restrictive than RPM's resonated stealth GPF Delete unit, so I'm hoping that the resulting flow restriction will sort out the drone. Although it's a very simple job to swap them over, I don't have access to a ramp so I've had to book it in with my local garage next week (the same one that fitted the GPF Delete). I'll have the answer Wednesday evening after I've taken the car for a blast up the motorway.
If it works, I'll not need to modify the system any further and will just sell the Resonated Stealth GPF-Delete unit, keeping everything else as it is. The problem will be if refitting the OEM GPF doesn't work and the drone is still here ...

What is the next step you agreed with Dan ?

Nothing has been 'agreed' per-se; Dan suggested that an additional resonator might be the solution. Designing where to put one will take time. Given that he's extremely busy with so many other things, the fact that the weather is so crap here and that Christmas is soon upon us, I'm not in any rush. I have my Plan A (above) to try out first.

Thanks for your interest and I hope that you manage to get a satisfactory resolution with your own problems.

-CB-

 

[telelaci]

It could be that the tracking number has been created with the Courier (for admin reasons) but that the parcel has not yet been collected? This might indicate that your item has not departed from RPM Performance due to a manufacturing delay perhaps.

This is how the tracking looks like:
---------
P2G109077817
Waiting for confirmation from the courier.
We are waiting for confirmation that the courier has your parcel. If you already dropped off your parcel, please allow up to 24 hrs for the tracking to update.
From: United Kingdom
To: Hungary

Drop Off:
15/11/2022 (Scheduled)

Delivery:
28/11/2022 (Estimated)
------------
And this parcel never was picked up and never will be picked up by the courier or dropped off. I know this, because this is not the first "Your order has been shipped" message that I got from him. This is fake it's, it's not the reality.

What other order is more urgent and much more important than mine ? I've ordered it more than 4 months ago. Why doesn't he answer my mails ?

What production delay are you talking about ? I've ordered and paid for it: "Order No. 11674 Placed on Aug 4, 2022". You ordered your same exhaust 55 days later (almost 2 months) and you already have it. I don't, and I have no ETA either, and I have no hopes either. I can't communicate with him, but I have a fake tracking label (not the 1st one).

I'm living with it for now but, having to avoid using N mode on an aggressive throttle otherwise it makes my brain and internal organs rattle.

Yes I know how bad the drone is. You feel that the source of that loud deep buzzing is inside in your head, and your brain starts melting soon. Absolutely unbearable.

The first stage of my experiment is to refit the original GPF, which is obviously more restrictive than RPM's resonated stealth GPF Delete unit, so I'm hoping that the resulting flow restriction will sort out the drone. Although it's a very simple job to swap them over, I don't have access to a ramp so I've had to book it in with my local garage next week (the same one that fitted the GPF Delete). I'll have the answer Wednesday evening after I've taken the car for a blast up the motorway.
If it works, I'll not need to modify the system any further and will just sell the Resonated Stealth GPF-Delete unit, keeping everything else as it is. The problem will be if refitting the OEM GPF doesn't work and the drone is still here ...

I very hope it will work. We will see in the next week. If it won't work then maybe you have to omit the Back-Sytem and you have to use everything else: downpipe, flexipipe and the mid GPF delete. It will be loud and tinny, but it won't drone.

Nothing has been 'agreed' per-se; Dan suggested that an additional resonator might be the solution. Designing where to put one will take time. Given that he's extremely busy with so many other things, the fact that the weather is so crap here and that Christmas is soon upon us, I'm not in any rush. I have my Plan A (above) to try out first.

Thanks for your interest and I hope that you manage to get a satisfactory resolution with your own problems.
-CB-

I don't think he is so busy. I think that is a false excuse only. Why would I think that my order, is not important and not urgent, and there are much more important customers and I have to wait. I don't think so. This is not a proper excuse. Maybe I'm not so forgiving and naive as you are. Four months is four months. He can't bluff that out. Neither the last month without the promised "resonated pipe" if I pay extra 20 pounds for shipping. He is not a good man, not a fair man but a liar who plays ostrich when necessary. Head in the sand and problems are gone. No responsibility and no response at all.
Thanks, but I don't think I could manage any satisfactory resolution, because I'm not the person whos making the action, I'm just a passive enduring customer. I understand that I will never get that I ordered, and he doesn't care. That's an offence, a personal insult and I have to look for my revenge, and I think the HMRC will do the job. I got no invoices.

 

[Cholmondeley-Biscuitt]

Getting back to the original topic - My OEM GPF is now prepared and ready to go back onto the KonaN to try and rectify the drone from the bigger bore gpf-back exhaust system. I gave the oem unit a full hand polish, a respray of the collar, a sand and spray of the (once rusty) nuts and a good application of 'coppercrest' on the bolt threads. It'll now merge seamlessly with the rest of the shiney steel system rather than look like a big brown discoloured blob that it was when I had it removed!

 

[Deleted member 2480]

This is how the tracking looks like:
---------
P2G109077817
Waiting for confirmation from the courier.
We are waiting for confirmation that the courier has your parcel. If you already dropped off your parcel, please allow up to 24 hrs for the tracking to update.
From: United Kingdom
To: Hungary

Drop Off:
15/11/2022 (Scheduled)

Delivery:
28/11/2022 (Estimated)
------------

He has used the cheapest nastiest company ever parcels to go so probably with Evri (aka hermes) when it would have been cheaper via royal mail.

 

[telelaci]

He has used the cheapest nastiest company ever parcels to go so probably with Evri (aka hermes) when it would have been cheaper via royal mail.

That is not the problem if its cheap. The problem is it was never dropped off at courier. It was scheduled a month ago. 15/11/2022
It was only a trick to make me calm. He did this before , so I had no huge expectations about dispatching the parcel.

 

[Deleted member 2480]

That is not the problem if its cheap. The problem is it was never dropped off at courier. It was scheduled a month ago. 15/11/2022
It was only a trick to make me calm. He did this before , so I had no huge expectations about dispatching the parcel.

have you had any response from them yet?

 

[telelaci]

have you had any response from them yet?

Nope. This was his last email after a complained of wrong version (I got non-resonated without Helmholtz resonator instead of resonated exhaust that I ordered and paid for):
-----------
Nov 11, 2022, 8:54 AM
Hello,

No it won’t be too loud as the vehicle starts in comfort and you’re not running an aftermarket downpipe. A resonator will only change it around 5-8db so it’s not going to completely change the sound at all.

What I’d suggest is keep it all and send us £20 to cover the shipping and I’ll make you the new resonated part of the mid pipe and send it to you. This was you’ll have both setups and can do some noise comparisons.

Just remember a resonator removes “resonance”.

Thanks
Daniel Barton
Managing Director | RPM PERFORMANCE
-----------

Look at the date. I paid the requested extra £20, in spite of the fact that he made the mistake and sent me wrong product. I just wanted a quick solution after 3 months waiting. It was his fault not mine, and he wanted extra fee for it. OK, no problem, I did it. Since Nov 11 he doesn't answer mails, he sent a bot-mail "Your order has been shipped." and the above mentioned fake tracking number from Parcel2GO.com
---
Order Reference: P2G109077817
Contents Weight Dimensions
kona n res rear section 2kg 70cm x 10cm x 10cm
---
This parcel never got dispatched. The drop off was scheduled at 15/11/2022, but never happened, the courier is still waiting for the package to pick up. Now it's 4 months + 9 days and counting. No communication at all. For sake of curiosity it's very strange that he measured 5-8dB difference with his sound pressure equipment (between resonated and non-resonated), but he doesn't know (!) that 6 dB difference means exactly 2 times less sound pressure, 2 times less loudness for the ears. It's a logarithmical scale and 5-8 dB that he measured is a serious difference. I won't get ever that I've ordered and "omg I'm so busy" is not the real reason. Are there customers with 5 months or 6 months long orders and I'm in a low priority waiting queue ? I don't think so. There is something else we donno. He is a shady person, and he lies and this can happen to anyone who makes business with RPM Performances. I buy everything on the internet Amazon, eBay and many other shops. Everything. I bougth Forge (U.K. also) Induction Kit + turbo elbow + blow off valve (they are excellent), I bought stage 1 ECU remap for Kona N at Courtenay Sport (U.K. also, it's awesome, that firm is a genious) and but never happened similar thing to me on the internet. I paid almost £1100 for this exhaust + £20 extra later, and he doesn't care.