I installed Staintunes late in my first season of 2003. I like them. They have a nice rich sound, I think. They aren't as loud as Sceptres, which I have heard running beside mine, and they certainly aren't as loud as some of the Big Dogs and Harleys I've heard firing up down at the water hole. Still, they get your attention when you get on the throttle, or when they are under a load like climbing a steep hill. They put out a nice, tolerable growl when cruising at highway speed.
I think the Staintunes give you a definite HP increase as long as you open up the intake too. That's really the key, you have to open up both the intake and the exhaust. I just installed a Freak kit this spring and WOW, what a difference. I'm really happy with my setup now. I haven't had it dynoed, so I can't give you numbers.
I pulled the pipes off this spring and cleaned them up. I had a little yellowing from the heat, but that polished right out. I was happy that I didn't find one speck of corrosion. They should last forever.
Regards,
Cody