I usually play with Sportsters but am building a Street Bob trike . The Street Bob now has an S bend rear pipe . The system now has 2 completely separate pipes and mufflers not connected with a balance tube between the front and rear pipe .
What are you concerned about ? The S bend pipe or the 16 1/2" mufflers ? The S bend in the rear pipe makes both pipes equal length (pretty much). The total length of the system is what counts , at least with Sportsters it does . Unless you have a 'built' motor you should be fine . Sportsters (usually) run best with a total length of 38-40" system and the bigger bikes do need a little bit longer system .
Most people change out the mufflers to get a better sound out of their scooters and usually because the bike sounds louder and has a different tone they assume that the bike is faster
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There are always a lot of opinions on exhaust systems . All I can say is try the system out or make a call to Frankenstein and talk to them on your concerns or wait for others 'chime' in on what they are running .
Lance