I bought this from a guy that makes dirt track exhaust and he owned a 690 smc so he built one for his bike. It's bigger diameter from head to mid and tapers up to a reverse megaphone supertrapp tunable end. Fit was perfect, welds were perfect. I rode up the street and first impressions on sound were quietier than my leo without the quiet core insert on acceleration but louder on decel. It's a one off exhaust, got it for a great price,builder has been making dirt track exhausts for 20 years and built it to perform for mid to over rev. I'm racing in two weeks in Texas so it ought to be fun testing this out.