Offshoreonly.com - HPI Exhaust Mufflers

I run those HPI's(transom mount, not clamp ons) on my Top Gun with modified 540HP 502's. I put them on when I installed the new engines so I can't say for sure how they affected HP and speed. They sound great. Quiet enough around the dock but still a nice rumble. The inside water flaps seem to rattle around and make a lot of noise but I hear they all do that??? Aty first I thought it was an engine knock until i realized it was coming from the mufflers. I was a little surprised to see rust stains on the mufflers after one season. None of the other stainless hardware on the transom shows rust. I'm not sure what grade of stainless HPI uses and how it compares to other brands. The stains did come out with a little polishing though. All in all I'm happy with them but I don't have anything to compare them to.