Well im looking into just gettin a 3inch downpipe for my 2003 monte carlo ss. What are some things i would have to worry about with doing this?

 

You are NA

Get the 2.5". Get the bolt-in, and you should easily do it with the car on jack-stands.

 

the 2.5" is plenty big and recommended for NA applications. the 3" ones are for S/C applications. the pipe will throw a cat efficiency code or something similar. nothing is actually wrong, there's just lots more flow there so the ecu thinks there is something wrong. people usually tune this code out with a custom tune or a canned pcm from ZZP and have no problems as far the the DP goes. overall, it's a good mod that many would recommend. there are many past discussions on this topic that can be accessed via the search tool.

 

so i can get the zzp 2.5 offroad right? Wouldnt i be needing a new 02 sensor or not. Im probably later down the road going to put on the rest of the exhaust when i have the money

 

Offroad pipe means no cat. I would recommend getting the 2.5" 304 stainless steel bolt-in with cat.

The only way you would need a new 02 sensor is if your current one got fried into the downpipe and a shop is replacing it for you and won't let you leave without the 02 sensor haha

 

if you deleteing the rear 02 sensor in the pcm you do not need new 02 sensor for the back one if that's what you asking .

 

Well do i really need a CAT? I was just lookin at a downpipe and having no exhaust out the back of my car just the downpipe under the car

 

I would recommend the cat for a few reasons. One emissions, two it's illegal not to have a cat, and NEVER do an open exhaust on the downpipe on our engines, it will sound HORRRIBLE

 

i think im going to buy the 2.5 with cat then go from there would this be a good start?

 

That would be an excellent start!