I drive a 1996 GMC Sierra with the Vortec 350, and would like to run true dual exhaust, either pull the cats, or leave them, with flowmaster 40s.However I noticed that I have o2 Sensors after my cats. If I pull the cats, wont the engine get the wrong signal from the secondary o2's and run rough? Just wondering what my options are.

Thanks,
Darren

 

i got the same prob, i just threw on a super 4o with dumps, sounds alright, but i think the cats are choking it. its an 07 nbs that is under warranty. i've heard some have the check engine light come on and some don't which i don't understand. then with a power programmer you can shut the rear o2 sensors off, or you can do it manually with a (finger stick) what ever that means

 

I have an 01 silverado with 2.5" pipe from teh manifold to teh mufflers, no cats, Flowmaster Super 44's and no tailpipes or turndowns. Sounds awesome! I haven't had cats for 3 1/2 years and haven't had any problems at all. The O2 sensors in front of the cats adjust the air fuel mixture, the rear ones tell teh computer if the cats are working properly. My check engine light came on, but I just took the instrument panel out and put a piece of black tape over the light.