Hey all,

I have bin reading on the net and there are some people that lose boost when adding a free flowing exhaust like a cat back or full downpipe + cat back. Are you guys seeing this??? I can't imagine this to be true because the evo runs a closed loop boost contral system??

Thanks
Eric

 

Yes.. common consensus has been that you can lose a few PSI of boost.. Its more prevelant with full exhaust systems than just a Cat back though.. Even if you lose boost, you are actually still gaining power... The other mods like boost controller and S-AFC (Fuel computer) work better..

 

I don't agree.

You will not lose boost if the stock boost controls are in place such as on the evo. If you have a manual boost controller you will need to re-adjust it to get your boost level back up. This topic has been covered in detail elsewhere in the forum.

 

Huh? Lose boost? Heck no, you gain 1-2 pounds due to the exhaust being able to exit the turbo quicker. I had to dial mine down with the MBC after doing the exhaust swap. It had gone from 20 psi to just over 21-almost 22.

 

Oh yes with a MBC you will have to adjust after adding in a free flowing exhaust. But I was wondering is the factory unit able to adjust to a full free flowing catless exhaust.

Thanks for the replys
Eric

 

Also, I was looking through Pruven's website. They said you will lose boost with their axle-back exhaust (unless you have a MBC). I'm not sure if this applies to full cat-back or other systems.

 

Yes, that's were I saw it. But I also understand the first few EVOs in the country did have boost problems unitl solved them. Witch is why I going to have to assume that you will not lose boost with a free flowing exhaust system with the factory closed loop boost contral system.

Eric