Pro, the 3" will allow you to mod further, but at that point you would probably just want headers.

Con, the 3" will lose some torque feeling.

 

i got the 2.5 downpipe and the plog and i must say my mpg actually increase along with a nice little rumble

 

2.5" is fine if your not planning on modding very much. 3" would support more mods for more hp but without doing the mods it allows you will feel a little loss in low end.

To answer your question about the rear o2. Once the code is deleted the sensor is turned off so whether it's there or not it doesn't matter. They make o2 bung plugs to plug the o2 bung if you decide not to install the rear o2.

 

If I was to get the 2.5" downpipe how many gaskets would I need and of what size? ZZP have them?

 

I am going to get the 2.5" catted downpipe from ZZP. What gaskets from their site do I need as well to make this a quick one stop shop thing. Dont want to get under my car nad not have evreything. Pictures would help as well. Thanks!

 

If you're going with the 2.5" downpipe I would do a little shopping around before dropping your coin on the ZZP. There are several replacement downpipes on the market (Magnaflow/Walker/AP) that flow as good (or better) then the ZZP downpipe. Save yourself some money. The only thing you 'gain' on a non-modded car with the ZZP downpipe is bragging rights that you have a 'ZZP' downpipe. The gain from removing the u-bend will be minimal.

 

Like I said a few times already I believe the zzp downpipe comes with the needed gaskets. Email zzp to be certain of this.

 

I would also recommend the 3' downpipe from Zz. I got one on my dale jr awhile ago. It did not change the sound of the car much (if at all) and after that and a powerlog I was able to drop pulley size a little bit.