2nd weekend at the track with the grp21 and wow..it just gets better and better! over 10 minutes per tank, very smooth power and lots of it.....mine is stronger and pulls harder then my Ninja B01A, 21-5kt (modded), and has more then my Max Power M5 had. All the while coming off the track at 200 degrees...tops! Running 30%, GRP 4 plug (I was using OD97T and they worked well, but I tried a GRP #4, and my temps came down about 15-20 degrees and the tuning window is a little bigger), 1 additional thin copper shim (which will come out for the next race) and Dynamite 53 pipe. This is likely my favorite motor I have ran to date (and I really, really liked/like the M5). Great job GRP!