Well, my pacesetters come tomorrow, so i've descided to get a jump start on gettin it ready, I just took the y pipe off the manifolds, and I see 4 02 Sensors, And as far as I know pacesetters only have slot for 2.. I might be uninformed, but im just trying to figure out what is needed to install these bad boys! Help would be greatly appreciated!!!

 

The rear O2 sensors are for monitoring the cats. If you got the PaceSetter Y-pipe also, you're gonna either need O2 sims for the rears, or have them turned off via HPTuners, LS1Edit, or through a custom tune (PCMforLess, Nelson, Westers, etc.) You can run without the rear O2's in the mean time, you'll just get an SES lt and codes for the rear O2's.
If you didn't get the Y-pipe, you're going to need a muffler shop to do some cutting and welding for ya.

 

Bingo, and if you do decide to run without them without any of the tuning techniques, you'll get VERY bad gas milage. I know, cuz my Tacoma is that way. Well, it was, until I went boosted, then the stand-alone got rid of the 02

 

i have no 02 sims and no custome tune to turn it off and my gas mileage never changed

 

Nor did mine. Well, actually it went to like nothing when I first got them, but we all know why. However, I can get more than what I used to on the highway now.