Updated sound clip of my '96 Ultra with PSI ModBlaster pipes for comparison to an earlier clip with PSI StockBlaster trail pipes.

There is far less baffling in these than the StockBlasters. Note difference in tone at idle to my other video.

Engine is stock besides clutching and jetting. Several have asked about jetting. Please do your own research and check your plugs/piston wash if you are trying to tune as every sled is different.
At time of video sled is running:

Unmodified 38mm Mikunis
PSI Needles in 3rd position
410 mains (@800' elevation; will richen below 10*F)
P-4 Nozzles
30 pilots
2.0 slides
Unaltered airbox
91 octane non-oxy pump fuel

Clutching is a work in progress:
Primary clutch weights are 10-58 with a 140-330 primary spring
Secondary is still being sorted out