I am looking at buying an aftermarket exhaust system for a ZXR250C and have had mixed reports on what the best option is. Any suggestions would be great. I have heard that the megacycle muffler can cause flat spots in the carb, can anyone confirm this?? The system i have found and am looking at buying is a twin muffler with new pipes 4 into 2. Has anyone ever seen one of these or had one?