i just finish insatling my magnaflow cat back system, the system is a 3 in for the lt1 and i have pacesetter long tube headers and the matching y pipe. thw cat back and y pipe ovelap each other and i could easily cut the magnaflow pipe to put a cat in but i would rather have a sraight pipe to the muffler. What do you guys think and if anyone knows how much power will i gain from no cat. thanks

 

2-3 hp if they're high flow cats.

 

the cats were stock but cannot be used becuase there 2.5" inlet/outlet.

 

Personally, I would leave it off. The place where you want to mount it is so far from the fresh exhaust gases, the cat will not be able to heat up properly and be as efficient.