ok will a catback cause a little leaning or will it cause the car to get a little richer?
i dont want to lean the car out!

and if i get a tune for a catless test pipe and i need to go back to stock for inspection will i pass?

 

bump....anyone?

 

I doubt an exhaust will cause any serious leaning conditions nor would a flash for a catless w/t the cat temp installed cause you to flunk a **** test, but ask your tuner just in case. An intake however, such as the HKS RS, will cause lean conditions but DF has a nice tune for those units for you to get some #s.

The worthless cat factory installed on the evo locks up lots of performance: when I replaced mine w/t a test pipe and a cell fix, I had to turn the boost down because I gained a solid 1 to 1.5 psi and my 3rd gear 30-70mph pulls were 10% quicker.

Make sure you have some spare 3" gaskets and a torque wrench if your going to be temp intalling that cat once a year and also test for exhaust leaks.

PS the factory cat bolts are a ***** to loosen, I had to get a 2' breaker bar

Also the best way to make sure you don't lean out unexpectantly is to get a walbro 255lph fuel pump, make sure it's installed correctly. The stocker is only good for a stock evo

 

Wont do either it dosnt change the air fuel mix.

 

thanks Stevdalpiaz

this might sound dumb but would i be able to get away with know flash and know fuel pump and run just a test pipe and a catback and have know leaner or richer conditions?
or is that bad?

 

For the 1000th time, DO A FREAKIN SEARCH!!!!!!!!!!!!!!!

Exhaust has NOTHING TO DO WITH YOUR AFRs!!!!!

KNOW is not the same word as NO!!!!!!!!!!!!

 

If by "know" you mean "no", you'll be fine.