Hey now-finally a registered participant here. Have been lurking around for some time, great forum! I'm a YFZ guy (quad), I have a question that maybe someone can help with. I (actually my son) was approached by the boy's in brown (park rangers) at our local OHV park. My YFZ is equipped with the HMF slip on exhaust, and all the jetting that is required. I've also done the cam-mod and I'm quite pleased with all around performance. I took the bike in for a voluntary sound test. It blew 103db with just the spark arrestor and 100db with the quiet core I purchased when I bought the pipe. California is 96db-so I got a problem. The park rangers were quite cool about the whole situation. They kinda hinted around about a local guy (yamaha mechanic) that was doing r/d on exhaust's for the WR and YZF bikes. Said he had come up with a can from the KTM open class bike, and fabbed it up to work on the yamaha bike. Was right on the db acceptance level, but suffered no loss of power seen with acceptable db output. I just wanted to throw this out there, since I really don't want to give up any extra hp that I've worked so hard to achieve. I do know that more power usually means, more sound. I ride alot of the OHV parks here in CA, so need to stay legal. Sorry for the long first post.....kinda complicated.