Ok, so as some of you know I recently purchased a set of titanium ceramic coated JBA stainless "cat4ward" (shorty) headers for my '08 Burb 5.3L. This discussion is not about short VS long tube headers as all of that has been hashed and rehashed before. I know that with long tubes most people run an off road (cat less) Y-pipe and disable the downstream O2 sensors in their tune. With that being said. Do you think there would be any real advantage to gutting the cats or removing them completely and retuning the ECM to ignore the downstream O2 sensors??? Also if I did gut/remove the cats would there be any advantage to installing the upstream O2 sensors in the down stream location by using extensions on the wiring??? Of course I would put a plug in the upstream O2 sensors bung to block it off in the above scenario. I have been pondering this for a bit and thought I would run it by the good folk of this forum to get their thoughts/opinions. My reasoning for thinking about gutting the cats is this... The idea of ceramic coated headers is to keep the exhaust gases hotter. Hotter gases move faster than cooler gases. The hotter, faster moving gases in each individual header pipe create a suction/vacuum effect on the other header pipes/cylinders (scavenging) thereby causing more of the spent exhaust gases to be removed from the cylinder and allowing more room for fresh air and fuel into the combustion chamber which creates more power. Now with that being said, my thoughts are that with the cats in place right behind the shorty headers it would cause turbulence and possibly the pressure waves to bounce back toward the engine causing the headers to not scavenge as much as they possibly could. So by removing them you would be keeping the gases moving as fast as possible. Again I may be way off base here so that is why I'm asking the opinion of the forum. I have already sent an email to Lew from Diablew since he is the one who tuned my truck. I will let you guys know what he says. The idea of moving the upstream O2 sensors to the downstream location just came to me since the rear O2 sensors wouldn't be in use. I really have know idea what effects or implications there would be from doing this, if any. I know that guys running long tubes often relocate their upstream O2 sensors further back in the pipes because of the headers. Any thoughts on this as well... pros or cons???