Do You have a 375hp or 425hp motor? There is a company called Raymar (I think) that specializes in the 496 Mercruiser engines. They have deeloped a whole performance upgrade package for them. I e-mailed back and forth with them earlier this year. Mechanically Volvo and Mecruiser 496's are the same. Volvos have worse stock exhaust manifolds though, according to them. The only difference between the 375 and 425 motors are the cam and the computer program. They offer a reprogram for it to make it a 425 hp. So all you would need is a cam swap. Not too expensive if you can do it yourself. And no one would know at that point that your engine is anything other than stock. Also CMI makes a header package that supposedly adds 60hp to the 425hp motor. It will fit our Volvo's. It is even suppossed to be eaiser because Volvo does not bolt as much junk to their manifolds and risers as Mercruiser does. Any or all of these would make a pretty big difference on a 375hp for not much cash compared to a supercharger and if the quality of the workmanship is up to snuff should not affect reliability at all. I have decided to wait on doing my engines for now because all that times two and then two new propsets, because I can hit rev limiter now with a light load, is too much money for me right now. It was the only time I wished I had a single since I got my twins!