if i run a .21 5 port motor for my truggy instead of the .25 motor, do i have to do anything different on the clutch setup? and am i going to notice anything different?, i know i saw someone say the .25 gets up to top speed quicker but the .21 will pull longer down the straight

http://www.skoffroad.ca/racing.html

this is pretty much what my track looks like, so i dont know if im better to get the .25 or the .21.... i know some people say go .25 that way i have power like the .28 and gas milage like the .21..i justcant figure out what i shouuld do....most at my trck uses a .28 motor... im leaning alittle more towards the .25....whats your thoughts?


Thanks