I recently installed a magnaflow 2.5 catback and xtc 2.5 dp with high flow cat. My car threw a cel saying catalist efficiency below level, and system running to lean. I had an exhaust leak as well so i copper thcd that up and just got my gmpp header installed today and im still getting the same problem. Theres no leaks anymore and everything has new gaskets/hardware. Cannot figure out the problem. Anyone? This is pissing me off. I never drive it now and take the streetbike everywhere.

 

its cuz of the high flow cat...some cars will throw that code some wont

 

Re-tune to account for your A/F and you'll be ok

 

or he can disable the rear 02 sensor

 

is there a way minus tuning to get rid of it? someone on myspace mentioned something about a resister to me? Or if i went back to the stock dp that should fix it as well correct?

 

I have that same thing, but my downpipe is by ZZP. No CEL's here.

 

what are the exact codes that you're getting?