Exhaust change - few questions

[kamyk155]

Hello.
I want to change exhaust in my N with GPF but still want to be street legal if we talk about law and emission tests.
For now in my plans is change back of the exhaust only - GPF-BACK SYSTEM.
In brief - I will stay with oem downpipe, oem flexpipe and oem gpf.
I know that those three parts will be bottleneck for my new exhaust.
New exhaust I want in 76mm. Now I started to think about what to do with front parts of exhaust.
What do you think guys about this:
- buy new downpipe with 89mm-76mm with 200/300 CPI cat with euro 6 norm
- buy new flexpipe with 76mm-76mm
- buy dummy GPF with 76mm-76mm
And connect those parts to the new exhaust 76mm.

First of all - downpipe will be really expensive, flexpipe isn't a problem and dummy gpf only for show in case of control.
Summarizing - whole new exhaust should have still euro 6 emmisions and be still legal and less restrictions if we talk about car power.
Of course after those modifications car will go for ecu tuning.
Is this a good idea ?

 

[R Veloster N]

It works and will be a plus for performance. Even with the the GPF dummy, downpipe, flex pipe and GPF back exhaust, I'll bet it will still pass euro 6 emissions standards as well. Sound emissions maybe not but when is the last time anyone stopped, ticketed you and tested it?

 

[kamyk155]

It works and will be a plus for performance. Even with the the GPF dummy, downpipe, flex pipe and GPF back exhaust, I'll bet it will still pass euro 6 emissions standards as well. Sound emissions maybe not but when is the last time anyone stopped, ticketed you and tested it?

Do you know maybe what are oem dimensions of N exhaust parts ?
- downpipe is 89mm to ...... mm ?
- flexpipe ....... to ......?
- rest of exhaust 65mm ?

 

[kamyk155]

Anyone know maybe what is the difference between DUMMY GPF with silencer and without it ?
Any additional exhaust restriction in silencer ? Picture maybe ?

 

[Mr.Bubble]

The opf pipe is little bit shorter, no silencer and the holder in the middle is 30-40cm near to the opf

https://imgur.com/Kq46pdN

 

[JAYtheVET]

I was thinking of going the same route with Milltek/Remus exhaust and the rest Gruppenzwang up to the filter box. It's about 4.000 Euros just for the parts.

 

[R Veloster N]

Either exhaust is mandrel bent. If you go the DIY route, use mandrel bent piping or components though. Check your local exhaust shops, to see if they have a mandrel bender. Not crush bent pipe.

 

[r_anderson96]

I'm looking at installing an aftermarket downpipe on my car, from my understanding would I be correct in saying that in stock form, from the turbo its 89mm and downstream of cat drops to 70mm for rest of exhaust system, ie flex pipe, gpf etc. I'm not looking at upgrading my turbo at any point, but wish to do a stage 2 remap.

My options are: gruppenzwang DP 89mm to 70mm with possibility of using gruppenzwang 70mm flex pipe and gpf delete aswell 70mm. (not so cost efficient but keeps stock 70mm exhaust system)

Xfroce downpipe 4" to 3" downpipe but will this mean I will need to replace full exhaust system to 3" (cost efficient for DP and flex but possibly need to change rest of exhaust system?)

I understand 76mm is a better flowing system than 70mm but as I'm only going stage two stock turbocharger would I really need the system to be upgraded to 76mm? I'm essentially looking at keeping stock back box.

Sorry if the above doesnt make sense, can clarify further if needed. Cheers

 

[r_anderson96]

I'm looking at installing an aftermarket downpipe on my car, from my understanding would I be correct in saying that in stock form, from the turbo its 89mm and downstream of cat drops to 70mm for rest of exhaust system, ie flex pipe, gpf etc. I'm not looking at upgrading my turbo at any point, but wish to do a stage 2 remap.

My options are: gruppenzwang DP 89mm to 70mm with possibility of using gruppenzwang 70mm flex pipe and gpf delete aswell 70mm. (not so cost efficient but keeps stock 70mm exhaust system)

Xfroce downpipe 4" to 3" downpipe but will this mean I will need to replace full exhaust system to 3" (cost efficient for DP and flex but possibly need to change rest of exhaust system?)

I understand 76mm is a better flowing system than 70mm but as I'm only going stage two stock turbocharger would I really need the system to be upgraded to 76mm? I'm essentially looking at keeping stock back box.

Sorry if the above doesnt make sense, can clarify further if needed. Cheers

Also, is it possible for 76mm (3") to meet up with 70mm (2.75") pipework, for example 89mm to 76mmDP, 76mm flex pipe then 70mm gpf?