I know about the quieter thing but not so sure about the performance loss. I switched from logs with OT pipes to tt headers and the quiet factor is large....we can talk without yelling now. Also, at idle with the tips below the water surface I'm pretty sure it'll pass any db check. With that, the Sheriff's don't even bother looking at it. We're real happy just in the fact our ears aren't ringing for 30 minutes after a run.
As far as the performance, I don't "think" there would be much of noticable loss.