Down Pipe

[GTPJIM]

I am considering a ZZP down pipe, if I were to buy a 3" catless DP will I be able to attach it to my existing Cat or should I just order the 3" Catted DP, which option is recommended?

[Odi]

If you want to keep the cat order the one with the cat.

[stealthee]

Yeah, if you need the cat order the catted downpipe. It's what I have on my car.

[theaceofspades]

You will throw a cel for cat deficiency because it's so high flow compared to gms stock settings

[stealthee]

I didn't throw a CEL, but then again mine came with a built in "defouler"

[REDCRAPGP]

Yup you'll still set that code more then likely but depending on the year you can either use a o2 emulator or try the spark plug fouler trick or just get it tuned out.

[theaceofspades]

My 5 dollar fouler off eBay works awesome

[nik12937]

If you want ot make your own fouler "mod", get a two pack ofspark plug non-foulers from an auto store and drill one out with a 1/2" drill bit. Screw the unmodified one into the spot for the second O2 sensor, the modified one into that, and your sensor into that. You may also need a rear O2 extension.

If you have an 04-08, I wouldn't get the O2 simulator. Some people have no problems with them, others have their PCM go into a diagnostic loop until the O2 is replaced.

[blueguy]

Anything '01+ technically will have fueling issues unless tuned out.

It's hit and miss.

So it depends on what car the OP has.

[theaceofspades]

My 5 dollar fouler off eBay works awesome

Edit this post just had to order a longer close tipped on for my car. Makes no sense drove like 500 miles no code and came back last night so got another one


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[stealthee]

In the 2 years, or how ever long it has been, I have had the downpipe on my 07 my CEL has come on twice for the rear o2. I last cleared the code well over a year ago. I have gotten over 28 mpg on a highway trip. Looks like I got missed.