I know this isn't really a productive comment to the thread, but.... I'm in the process of building a big block, and was looking at these cheap gear drives. Ended up deciding that I didn't want a cheapo part in a spot that if it goes bad, the whole motor is likely toast. For about the same money as an import gear-drive, you can get a good quality billet steel double roller chain. I'll stick with the tried & true. After all, the noise is the only thing you're really gaining, no performance to speak of.