The Indifference Engine
Join Date: Sep 2007
Location: Edmonton, Alberta, Canada.
All it's going to do is move some hp to the higher rpm range. If you're getting it tuned soon and you can get them for a decent price I'd go ahead and buy them. I don't think they're worth it at stock prices if you're not looking for that extra 1/10th of a second that comes up when you're racing.
Brian MC, they work by changing the inlet length and diameter to allow best air flow into the cylinder at max or near max rpm. Stock the bike has to be "tuned" to work well at all rpms. But on the track or racing it doesn't really matter how the bike runs below 5000 or so, because you're only there when you're getting from the pits to the track itself.
It may not increase hp much, but as part of a well set up engine package can make a difference.
Of course I'm generalizing from a single example here, but everyone does that. At least I do.