I have them and really like them. IMO, they are the best looking pipes for the bobber, kind of old school looking. The stainless finish matches the head pipes really well. They are straight through but with the expansion chamber they are not obnoxious loud, they just add a deeper sound with a little more volume. But, I'm still running the cat crossover.
No seal is needed on the bobber.
2018 Triumph Bobber with Triumph brown quilted seat, BC Sleeper Pros, Booster Plug, leather fork bag
2009 BMW R1200GS Adventure
2006 Harley Roadking