I ride with a guy that has a 2001 YZ426. He has a white brothers E-series pipe / stock head pipe. After we stop riding his headpipe is blue for the first 6 inches coming off the head. On my 2002 my head pipe is tan throughout. Is there something wrong that you can forsee from this blue head pipe? Perhaps too lean. He does experience some decel-popping but not an excessive amount. Is there something wrong? If so, what should I look for?