I have a 07 Ls Cobalt and i just got some headers and a cat back exhaust however i dont have a down pipe. should i just get the stock down pipe cut and fitted to the exhaust or can i get a different downpipe without the catalytic converter? will running the car without the second O2 sensor make it run rich?

 

It will through a code for emissions out of check, that's all your second o2 sensor controls. You can purchase a catless downpipe from a lot of different suppliers, zzp is a good one. Or you can go your route and just hack out the cat, it will most likely add a raspy/ricey sound to your exhaust.

Btw on these cars its a header, we're not a v-6/8 with 2.

 

The second 02 sensor is only there is judge if you have a cat.

So it will throw codes for no cat, but it will not affect the rich/lean mixture of the car.

 

Thanks for the advice. but even though its a after market exhaust and header there would still be a ricey sound? also if i got a catless downpipe how would i know it will fit with the other after market header and exhaust i got

 

what brand header and cat-back did you pick up? for down pipe your best option is probably a 2.5" ZZP high-flow catted version, not many other brands for a 2.2 and if you go catless it will sound horrible (although some people do like that )