siberianhusky

I've got one of the ST q-18 pipes, havn't got it trimmed to length yet, It seems like a really heavy pipe! It weighs more than a K&B 7.5cc muffled pipe! about twice as thick aluminum in it! I've only got about 4 tanks through it so I can't comment on performance, it is quiet, really knocks the high end off the sound, leaves more of a deeper tone.
Make sure to take it off the boat and turn it upside down to drain out of the outlet hole when you're done running. The way its designed traps a lot of oil in the pipe that can only be drained by removal and standing it on end.
The ST header if you are using that needs a lot of work with a dremel before use. It comes nowhere near to matching the exhaust port, needs widening a lot and a bit more height to get smooth exhaust flow. The gasket that they come with is a horrible match, I tossed it and lapped the flange flat and bolt it straight to the engine with a bit of high temp gasket spray. If I can find some thin soft copper stock I may make up a couple of copper gaskets to try.
Not sure if I'd get another just because of how heavy it is.
I have access to all the top end tuned pipe design software from a 2 stroke tuning and racing wizard here in town, both of us are RD350 fanatics. If I was better with a TIG welder I'd love to make a few pipes to try! I know I'd be blowing holes through that thin aluminum or sheet metal. Would be easy enough to roll up the cones on a slip roll.
Wish my old welding shop teacher was still alive, day one he tigged a pop can back together to show us it can be done! That was 25 years ago though!
Hmmm with a jewelers torch I could braze thin sheet metal. The bronze seams might look neat!