I have 2 1/2" running from the cat to the muffler. I have a 3" cutout in the box and got a quote for 3" pipe all the way to the muffler. It would be $150 for the pipe & cutout install. Is this worth it since i assume the muffler is 2 1/2" inlet? Would i need a new muffler it get the benefit of the bigger pipe?

 

You might get a very small gain by just replacing the i-pipe itself. Looking at your sig, do you have an aftermarket catback? It would probably make more sense to just flip the coin and get a system of your liking that will already have the 3" i-pipe included.

 

who the heck put a 2.5" muffler on a supercharged V8???

just replace the hole damn thing...you should see some very noticable gains

 

The exhaust came with the car. I installed the supercharger and headers recently. I am now looking for the whole system to breath. I wasn't sure what the horsepower needed to be to go above 2 1/2" pipe.

 

well considering it's not uncommon to see 10-15hp from a standard catback on a bolt on LT1/LS1...and that's going from 2.75" pipe to 3"....i would think with the added power of a SC you'd be easily choking the engine by 20+ hp.

what kind of headers did you get?

i would consider doing some true duals to realy let that thing breath