Hey guys, what do you think will give me better overall performance? Gutted cats on the stock piping or a brand new 2.5 inch Rotary Performance high flow cat. I mean no cats should flow better since there is no restriction, but would the 2.5 inch pipping increase the flow?

 

If you dont have to worry about emissions, then gut the cats. The hi flow cat is designed to flow better than stock but still pass emissions.

 

Cut the ends off the cat and save them, Measue the lenght of the cat. buy a length of pipe the same length of the cat and id of the pieces you saved. Slide the pipe in the cat, weld it in, weld the peices you saved back on. and bolt it up. or just put in a straight pipe.

 

Power gains from the exhaust is as dependent on smooth flow as it is free flow.If you gut your cat it could actually slow the gasses down which could be a bad thing.GregW has the right idea.If you have to pass emissions then a high flow cat is the way to go.If not a straigt pipe or a pre-silencer.