I have a W-B E-Series and just recently started experimenting with their quiet core insert. I was running 8 discs, so I just tried the core with 8 and found that the bike was almost as quiet as a stock CDN. pipe but the power and throttle response
were all but gone. I quickly added 4 more discs and found that the sound level did not increase that much, but the power was quite a bit better. That is as far as I got with it, and as it stands now, I can't imagine there would be any sound test that it would not pass. I do plan on modifying the quiet core by drilling out and/or removing some of the restricting plate washers. Hopefully that will put the power back near where it was without upping the noise to the point where I draw fire from the "sound sensitive" people out there.
[ November 08, 2001: Message edited by: Pete Z ]