Fmf mufflers are as good as they come , I have a complete fmf system on my ktm and its a great setup. If your refering to mini 4 strokes , the fmf 4.1 system is right up there , the muffler is welded to header I believe to ensure no exhaust leaks. It needs modifying to fit import bikes to fit larger subframe mount but they sound sweet. The header pipe tucks up nicely against the frame too and keep away from your plastics , I will probally get one some time soon , I really like the look of them