I use the 38 with the 7.6 as the biggest on the 101. For me the Sl4 has less power than the sl3 and 2 and gives less lift to the board making it easy to control.
I would try a 34 for your 6.6 when you get really powered up.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.