The Supertrapp is a popular exhaust system on Harley
Big Twins and XL's alike. We offer Supertrapp
systems and we've seen many examples of our
customers getting great results when using them.
Often we get asked about how many discs to use.
Every engine combination has the potential to be a
little different, but we went to the trouble of dyno
testing disc packs from 12 to 26 on our '04
Sportster, which is a typical mildly modified street
bike. Here are the results of that testing:
All of these pulls were done on the same day, on the
same bike, as close in time to each other as
possible. As you can see, adding discs helped
midrange and top end power in all cases, and never
lost any bottom end power!
In general, we like this exhaust, it diffuses well
with lots of discs in it and gives a good wide
We also did a few pulls with the end cap and discs
removed, just to see what it did. Here we compare
the best one with the 26 disc pull above:
As you can see, you need the discs!
Supertrapp systems are readily available from NRHS,
even if they're not on our web site right yet. Give
us a call at (303) 833-4500 and we'll fix you right
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