Re: Performance parts
For bolt on, there is gearing which does make a big difference. There also is the bolt on shifter kit for a multispeed bike, which allows use of all your gears so you get kick arse acceleration without giving up top speed.
For actual engine power there are some bolt on expansion chambers (huge difference) and bolt on carbs and air filters. All will help, but as mentioned are useless without at least matching the ports with both manifolds (again - HUGE difference) . So invest the money in a Dremel tool, several packs of sanding drums and go to town. It's actually pretty easy to match the ports by sanding the manifold with a Dremel. Intake has all kinds of weld bead and stuff, exhaust is just WAY smaller than the head exhaust port (terrible). PLUS you'll need to make your own gaskets - the gaskets can be the choke point - and that can't possibly be good!