I opened up my can on 05 wr450 and removed only the 1st baffle, left the spark arrestor in and have no tail pipe. It has really opened up the bike. Now I went for a ride yesterday and the bike runs great but when the bike really started to warm upit started to pop on decel and wouldnt idle so i upped the idle and then the revs started hanging . The bike also became harder to start and when the bike was hot the hotstart still wasnt needed. I could also pull the hotstart in at idle and the revs wouldnt rise. I admit I wound up the idle abit to keep it from stalling but today I wound it back down. Ive already got a 48 pilot in so I think a 50 will be over kill, needle is a red #4, and bike runs great wide open so main doesnt have to be changed. I had the fuel screw set at 2 out and wound it to 2 1/2 and it didnt really change. The bike runs great all round bar the popping and hanging Ive only got this week to sort it out coz theres a race on sunday, and i dont really have any ride time through the week> I havent played yet but I am thinking of richening the needle 1 clip, but apart from that this thing got me a bit stoked coz I think the jetting is rich enough, any thoughts?? I posted this in the exhaust mod thread yesterday but moved it to a new one today. What I did today was wash the bike and let it warm for a bit and took it for a ride round the block. Now there ws no popping and when I pul the hot start the idle rises which all seems fine, but the bike was not really warm like when you go for a good ride.????