As Tom says I did it to my 997 turbo as I ran out of time to finish the fabrication of a custom exhaust and was running the car at terminal velocity.
I picked up around 10bhp - from 530 to 540bhp. I expected a little more than this but if you look at the way the standard exhaust flow is routed, removing the cats still leaves quite a convoluted path. There is zero additional drone - which i was happy about as I hate drone!. You get a lovely whistle from the turbo too, and more rasp so from a sound point of view it's fantastic.
There is an addional mod you can do to free up flow which is to cut a hole in the cat outlet to partly bypass one of the baffle sections so that flow pretty much goes straight to the tail pipe.
M
I picked up around 10bhp - from 530 to 540bhp. I expected a little more than this but if you look at the way the standard exhaust flow is routed, removing the cats still leaves quite a convoluted path. There is zero additional drone - which i was happy about as I hate drone!. You get a lovely whistle from the turbo too, and more rasp so from a sound point of view it's fantastic.
There is an addional mod you can do to free up flow which is to cut a hole in the cat outlet to partly bypass one of the baffle sections so that flow pretty much goes straight to the tail pipe.
M
