OK, on my 2000 YZ426F, I got the new headpipe from GreenKLX (thanks again!) and I installed it with a new Yoshimura RS3 off road slip on muffler unit. Started the bike and could not believe how much engine noise I was hearing with the new system in place. I haven't had it checked for db's but I would guess <96db's. The system I took off is a full WB E series running 10 discs with a db killer in place. It is now on the shelf waiting for a new home. Too loud for the forest. If you race MX or HS where sound is not an issue (I know, its always an issue) its a good unit. I would guess that its close to 100db's. It can be repacked, but I have not done it. That will help with the db's. Now, I'm sure you all want a ride report and I would love to give you one, but the jetting is now way off. I'm out 7-8 turns on the fuel screw, so that's not good. It does feel like it has more low end and just a twitch less on the top. For the riding that I do, the slight loss on the top is no big deal. Once I get it jetted (JD kit?) I will update again.