Altough (I hope it is spelled right) I'm aware of all the fuss about loud pipe . I decided to go with a stock YZ pipe on my wr. An fmf was available but cost toooo much ! And I confess that I took this decision based on all the inputs I received from this group. I have to say that I don't regret it Thanks guys. I feel much more "fun" out of my throttle. But I have to ask, what are the indications I have to look for proper jetting ? Even if so far, the bike runs ok. No problem with starting, and while twisting the throttle I didn't feel any misses. I still run stock jetting. The snorkel is removed but I left the lid "with 6 1 inch holes" so I could have a place to place the battery. I also installed a Unifilter. I'm wondering if with my stock YZ pipe and the opened up intake, I have to go richer ? Even considering that the bike runs "OK" . May be I'm missing the best part of the blue beast if I don't ask ? I should be running a 162 (or165) main jet,(from the dealer charts). I run near sea level up to 1500 ft. Before I do any big move I want to be sure that the trouble will be worth it! Thanks for your infos!