Guys...I'm totally noob to brushless systems..please help me decide to choose these combos for my Slash:

EZRUN 60A + 8.5T or EZRUN 60A + 5.5T?

Im going to run 2S or 3S max...I also plan to put 17mm hex buggy wheels and tires for more traction.

My goal is to make her competitive to race with some nitro buggies at my local track (small sized but technical).

Please advise...Thanks.