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Engine Spark plugs

any idea how much it will hurt the mileage?
Depends on your driving style. Maybe 1-2 MPG, maybe more. In order to run more boost without misfiring, the gap needs to be tightened. There are other ways to compensate with an actual remap, but not with a “tuning box.”

In other words, you can’t have more power without sacrificing fuel economy. I’m not about to put the factory plugs back in and test this. I’m fine with the small drop in fuel eco.

You should monitor and document your fuel eco now and then you can report your changes should you get aftermarket plugs and a JB4.
 
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I can speak to this cause I drive 700km to work a week and the roads are fairly flat and straight with little to nonexistent traffic.
Stock plugs best on a 70km one way my best used to be 6.9L/100km very consistently Eco driving and a couple of times lower. Regapped HKS plugs is between 7.3L-7.5L/100km.
 
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Ordered the R2556G-9’s from spark plugs.com smooth and easy tranasaction and fast shipping ! Each spark plug also came pre gapped to .024. Thanks Cyngus for the recommendation !
 
Anytime you change plugs, you need to check the gap from the box. They aren't protected from bouncing around in the box and a small tap on the electrode can change the gap.
 
If you're forced to deal with gapping every plug no matter what, then why not just regap the stock plugs, would that work for the jb4? I don't mind paying for better ones if they're actually better or pregapped correctly though
 
The stock plugs may very well work since it is Heat Range 8. I ran mine re-gapped for about 3,000km but didn't want to risk it.
Initially the the earlier variants of this engine came with HR 6 and they kept blowing and then 7 and also blowing up.
If you're going to run Map 2 or more, you may as well get a colder plug!
 
I just ordered a JB4 and am looking to get spark plugs that will work with the higher boost, without me having to re-gap anything manually

I'm looking at https://www.sparkplugs.com/product.aspx?zpid=57050 , but it says the gap is 0.028" - Y0UKN0WITSCHRIS you say it came gapped to 0.024" ?
All four of mine came gapped to .024 and I ordered this exact same set tested them 3x just to make sure I wasn’t crazy and they were spot on
 
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Hello everyone,
I ordered HKS M45XL, in the specification it says that it comes with a gap of 0.6 mm, but in the instructions they say that you need to separate the spark plug to 0.7, I read some comments that say that 0.6 is fine but I need to certify that this space is

I bought the 45 because my car is remaped

Greetings
 
Does anyone know the stock plug part number and stock gap? Thank you in advance.

-M