if i cut out the cats and go with longtubes and a diablo tuner can i just leave out the back o2s and program them off or do they need to be back in?

 

yeah you can turn the sensors off with the tuner

 

just an fyi;
the rear ones Are Not sensors, they are Monitors and all they do is monitor catalyst efficiency.....

 

You need something to block the holes in the mid-pipe for them but w/ the tuner, you can just turn them off.

 

i'm not running a mid pipe, it had a set of custom true dual that was done at the local muffler shop, the guys used one side of the original pipe and made the other side from the cat back so i'm installing mac long tubes myself and cutting the cats out and gettin them to weld it back together.. (less expensive that way)