most people are running .21's in truggies ...me included ....for the reason of fuel economy .....most .21's are more than enough to power any truggy ...and your runtimes will be longer .....a .28 may have to much power and your wheels will spin a good bit on gas and coming out of corners....not saying they wont work ...but prolly 80% would use a .21 ....if the tracks you are running have many long long straights a .28 could be a good option .....