Hey guys I have a stock 2008 Evo X and today I intsalled a 3 inch cat back straight pipe to axle then 2.5 out to the tips no muffler. Sounds great but when im getting on it at about 6k rpms pulling hard it makes a studder like its hitting fuel cut of or somthing just for a split second then gets write back into it! does car need to be tuned for exhaust? overboost? any ideas will help thanks

 

You're more than likely hitting higher loads (slightly higher boost) which is making your car run richer and it's choaking on the amount of fuel. The stock tunes are really bad about this so the only thing you can do to correct it is to tune it out.

 

Ok Thanks for the info

 

Probably hitting higher loads and you are hitting the negative timing values of the stock map...

Or you are getting knock from how rich the tune has become...

 

Interesting, we installed a fully downpipe and exhaust on a stock EVO9 for a customer, we did a dynopull before and after. Stock eveything looked typical for the 9, but after the exhaust downpipe and test pipe, the thing went hard into the 17 AFRs above about 5K.. Anyways, the customer said he was gonna come back for a tune and was gonna park it.. Wonder if your having the same issue..

 

IIRC, the stock X is richer than a stock IX ever was... the usually Mitsu BS... make the the timing high and car rich as hell. But it is anyones guess without a wideband and logs.

 

the Tune and boost cut on his car is very close
he can simply come in for a quick adjustment that we would do for him on the house

 

man you guys are soooooooweet

 

base map ftw

 

I'm currently running a cat-back exhaust with no other mods, and I'm not having any issues. Are you hearing the popping sound when you hit the 6k RPMs? That is perfectly natural. Your exhaust system occasionally has uneven amounts of exhaust flow. When there is a surge in exhaust flow, you may hear a popping sound. Perhaps this is the studder you're referring to? The stock muffler will eliminate this sound.

I'm running the ETS V2 cat-back exhaust, and the mufflers are quite small. I imagine your system is pretty similar.

You might also want to check your exhaust to make sure there are good seals with the gaskets. You replaced the stock gaskets, right? If the pipes aren't sealed correctly, this will have obvious effects on performance.

Good luck

 

What kind of exhaust is it?