Thanks a lot so the next question would be which downpipe and cat worked best for you guys and is it the same as a "catback" exhaust system?

 

Downpipe is before the cat, so its not the same as a catback system. Usually a new cat is included with a downpipe. A catback system is called a cat back as it involves everything from the cat onward.

 

There are a few factors with the down pipe. Such as your long term plans.
- Do you plan to get headers? If so, they normally come with or require a different down pipe.
- Do you plan to keep your car naturally aspirated or do you intend to look into boosting it with a turbo or super charger?

Those are the two biggest questions I can come up with. If you don't plan on headers or running any boost, then I would recommend a ZZP 2.5" Downpipe with high flow cat. Here's a link about my install with pics of the stock vs ZZP:
'04 Monte Carlo SS - ZZP Downpipe

My exhaust is:
- ZZP PLOG
- ZZP Stainless 2.5" DP with High Flow cat
- Resonator delete
- everything else is stock (and I actually like the way it all sounds too)

 

nice pic looking exhaust, i dont plan on gettting a turbo or supercharger at all, i think im going to just do the downpipe and all the way down, so far what im thinking is an aftermarket dp....possibly delete the resonator....im not sure but i think i have 2 cats cause i do have 2 mufflers. what is the stock tube size, and whats a PLOG?

 

ok i have decided on what to go on for sure. heres the setup, im looking at a zzp downpipe with the cat, seen a few images from mike.(chibi) also the ubend and res delete. heres my concern, would this setup come with a port for the 2nd o2 sensor so that the check engine light dont go off, and also would i have to buy the pipe that would be replacing the res?

 

You have one cat and one resonator. On these cares, the pipe coming out of the cat is a "Y pipe" as it splits off to go to the two mufflers.
I believe the stock DP has an inside diameter of 2-2.25" (I actually cut mine open before I sent it in to ZZP for a store credit). I'm not certain about the rest of the piping back.
Again, I'm running on the stock Y pipe and mufflers. All goes well and Saturday I should have some shiny Magnaflow tips on them

A PLOG stands for Power Log. It's a product fabricated and sold by ZZP. It's a front exhaust header. It was found that the front manifold of the stock 3800 exhaust is a bit restricted. The PLOG allows it to breathe a little better. A pick comparing my PLOG and stock manifold can be seen below.

 

Most likely the high flow cat will set off the CEL

 

I think there is a good chance this can help resolve the CEL related to a high flow cat
https://montecarloforum.com/forum/pr...impalas-42773/

 

ahh so u do pcm service so would this erase the code or delete it from the pcm so that the code dont exist, and do u also tune to add hp and mpg gains?

 

He removes the trouble code from the PCM so it doesn't illuminate the light ever.