I am installing a catless downpipe pretty soon here, and I was wondering if talking out the third cat as well would be a good idea. I would just leave the resonator in, since I don't want the sound to be too high pitched and ricey. I've done it before on past vehicles and just hooked up an oxygen sensor simulator with good results. There are no emissions tests in Nebraska, so no problem there. Thoughts? Has anybody done this before?

Thanks!

 

What cobalt has three cats?

 

We have 2. When you install the catless downpipe you will have 0.

Are you seeing a resonator and calling it a cat? If so, don't remove the resonator.

 

So, there are no cats after the downpipe at all? Weird. And no. I won't take out the resonator.

 

There are not. Its not weird at all, most cars have a single cat some have two (newer have two) one for hydrocarbons and one for heavy metals

 

Gotcha. My old Cherokee had three, actually. But this is good news. Also found out I can disable the cat code with my tune, so it's all good.

 

I'm also assuming that Cherokee had more than 4 cylinders? The hydrocarbon/NOx cat is normally closer to the engine due to the heat required for the reaction

 

Nevermind the 3rd one, the 4th cat is where the real action's at here!

 

That's true. Catless downpipe plus muffler delete is a crazy animal.

 

Ok, all my ignorance on the cats on my cobalt aside, would it be worth it to get 3" tubing all the way back, since my downpipe will be 3" now?

 

Not completely necessary on the stock turbo but it shouldn't hurt performance on an LNF. You'd probably want a 3" all the way back if you get a bigger turbo but I see a lot of people still running stock exhaust on a lot of setups

 

Nope there is absolutely no reason unless you go bigger turbo.

Has shown to gain almost no horsepower.

 

Ok. I will save my money. Possibly going for a bigger turbo in the future.

 

Except the increadably sexy deep rumble

 

That is a pretty good reason in my book...lol

 

my ls1 had 4 cats. OEM

 

Your ls1 had 2 banks

 

3" exhaust sounds good though.

 

What about the resonator? I would have to get a new one to fit the 3" pipe?

 

Cat backs come with all the piping up to the downpipe. Some include a resonator and some just a straight pipe in it's place. That would just be personal preference on sound for you because there would be no loss or gain from having a resonator or not

 

stock exhaust is close to 2.75". It doesnt look pretty but damn, that is the largest diameter tubing ive seen on a 4 cylinder car from the factory.

 

Get a 3" downpipe - covers from the "up pipe" to the exhaust pipe.

get a 3" catback exhaust - covers from where the downpipe leaves off to the rest of the exhaust system.

Those two things will replace everything from the up pipe back. If you get a catless downpipe, you'll havve 0 cats in the system. There are plenty of exhaust options. Muffler/ no muffler/ no resonator/ side exit.

Turbo XS sells decent exhaust systems. I believe they have 3 - a quiet one (has resonator, muffler), a loud one (missing muffler?), a ******* loud one (no muffler or res - straight pipe).

ZZP exhaust looks decent too. You'll have to search the forums for sound clips, and fitment issues etc.

 

and 4 cats.

 

Makes sense to me

 

Just got the catless downpipe on. Definitely sounds different after about 3k and when I let off the throttle.