Originally Posted by shadoquad

The way I understand it, the FI get pretty good gains.

But, for the most part, custom exhaust is more about sound/appearance than it is performance, because what is 15hp in a 3300lbs car that's already pushing out "near as makes no difference" 300hp? It's a drop in the bucket. And if you've got other breathing mods already on the car, remember that the advertised gains aren't cumulative. They are all relative to a stock component where the rest of the components are all also stock. Exhausts, headers, cats, and intakes work a little different when you mix and match, so the gains aren't obvious. In other words, 15hp exhaust plus 15hp intake does not necessarily mean 30hp gain.

Just something to noodle.