exhaust + cats anyone?
 

Hi flow cats claim 15-20, cat back exhausts claim about the same. Do they add if you get them both? Anyone done Stillen or FastIntentions high flow cats and cat backs with a Dyno run? If they add, it should be 30-40rwhp.

1+1 doesn't equal 2. It's more like 20-25 whp based on others who have done exhaust+cats dyno.