I just got a full dr.d exhaust system off ebay and bolted it on my 05 wr450. Got it all buttoned up and went for a 20 minute ride on the railroad tracks. I came back and checked the plug to see how lean I really was. It was a kinda white so I went down three needle clips (all the way to the bottom) and reassembled. Went out down the driveway and could barely ride the thing! It had a HUGE sputter all the way till like half throttle that wasnt there before, then shot out like a bat out of hell. Then I came back went back up two clips on the needle and I felt very little difference. It still does the same thing. Am I not putting something back in? It ran okay the first time, then even now with only going one clip lower than what it was it still runs horrible. It almost runs better with the choke on, but pops like crazy. HELP!!