New exhaust for 1999 monte carlo 3.1 issue
 

I have been researching, and i wanted to turn my single exhaust ls 3.1 v6, into a dual exhaust. but the problem i hear alot of is that if you change the exhaust your check engine light will pop on due to lack of backpressure is there a way to get a better preformance exhauust, and not have any lights pop on. i basically want more deeper sound to my monte carlo, and as much performance as i can gain.

thank you Jacob

RE: New exhaust for 1999 monte carlo 3.1 issue
 

I am considering this as well. This is the first obd2 car I've ever dealt with (my 99 ls) and I don't imagine how that would cause a cel? Also, I own a Lincoln and people on my board always joke about the GM guys claiming they 'need' backpressure. Whats the deal with this? I hacked the mufflers off my Mark and killed all backpressure, and I have plans to cut out all resonators, and run straight pipes right out, and have driven in Marks like this and they run fine.

I am interested to see peoples' response to this. I have a small exhaust leak where the exhaust pipe leads into the muffler, that I plan on patching up with jb weld until I can either replace the muffler or do something else.

It looks like there are 2 cats, or is one a resonator? Also, where is the 02 sensor in this badboy, because if these cats are 'unmonitored' by an 02 I'll just gut em all out. That sound improve sound.

RE: New exhaust for 1999 monte carlo 3.1 issue
 

Actually I'll just patch up the muffler thats on it now. This will never sound as nice as my 4.6 so I won't try. Add a new muffler and enjoy!

RE: New exhaust for 1999 monte carlo 3.1 issue
 

You won't get a check engine light by any catback work on your monte (ok, maybe if you plugged it up really bad, so backpressure went through the roof- but not doing anything normal). On my 3100 96 ls, I drove around for a couple months with it cut off just behind the cat (long story)- and I never got a check engine code; before that I had a glasspack in place of the muffler, and a resonator delete.

As many have said before, don't do any cat back exhaust work for the puprose of gaining power- even a wide open- free flowing system isn't going to gain a noticeable amount ona basic bolt on engine, so it isn't worth it to pick one setup over another to pick up that extra 1/2 awhp. Instead- base your choice on what sounds good to you.