Lanmine657, going to 20% will be a very good idea if you are looking to smooth out the power and get some more traction. I just recently did some testing on 20 vs 30 and a much smoother bottom end is one of the things I noticed with 20%. Your fuel mileage will increase also as others stated. It will not hurt the motor by switching nitro percentages but you will have to retune the needles a bit and maybe a different glow plug. Good luck.