The m4 megaphone slip-on style, I don't see why I can't get any m4 off ebay from any other inline four cylinder bike and be ok for my f4? Right? I mean, with that type exhaust why should I worry about if its made specifically for a 600 cc f4 or not? As long as the fuel/air ratio is right after ip put it on.

Example; if I see a m4 megaphone slip-on on for sale and its off a yama r6 or a zx6 or any other 600 cc bike. It should work right? As long as the air/ fuel ratio is right on my bike I'm thinking it will work.

 

If anything it would only hurt performance only a tiny bit, I say try it out. My friend put one of those M4's on his 600RR because he didn't like the undertail, sounds and looks great.