Did a little sound pressure level testing today with the PC496 I picked up from a fellow TT'er a while back. Finally got the bike back together after some winter wrenching and some suspension work. These tests were run with a calibrated B&K sound pressure meter set to A-weighting, slow response, random incidence. Bike is a 2003 WR450, JD Jetting (for open stock pipe) and a recently re-packed PC496 slipon with spark arrestor screen. Bill provided three inserts for the PC496 pipe, they have a lead-in pipe of 1", 1-1/8", and 1-1/4" respectively. Here's the data: 1-1/4" Insert 99.6 dB @ 5250 95.0 dB @ 4000 1-1/8" Insert 98.6 dB @ 5250 94.3 dB @ 4000 1" Insert 97.3 dB @ 5250 94.3 dB @ 4000 Interesting (to me anyway) that the two smaller inserts tested the same at 4000rpm, but the differenc really showed at higher RPM. Sounds like lots of different places test at different RPM's so I checked a couple different points just for giggles. Hope somebody finds the info useful.