Back pressure and gas speeds are both effected by silencers.

The better the design of silencer then the more noise it stops for a given reduction in gas speed.

A decent exhaust will definately not lose as much power as the amount of boost you would have to remove to get to the same level of noise on a crap exhaust.


Exhaust technology just suddenly became a lot more relevant to modified cars in the UK, in places like germany all aftermarket exhausts HAVE to be designed with this in mind to get TUV approval AFAIK