just wondering which is the largest muffler you would recommend for a 250cc 4cylinder Kawasaki (ZXR250a). I was looking on ebay theres quite a few which are off CBR 1000's etc but i imagine they would be too big. But how big is too big? Would one off a 500 or 600 be too big also? Thanks. Also what are the positive/negative effect of different sizes. I want more power and a gruntier/deeper/louder sound, if thats possible.