Yes, 17.5 is best with me too. Faster is funer... At Aliso we are right on the edge for that little screw-together plastic chassis though.
But S-grips, yuk. If you don't go too fast, they work better.
My hope joining in here was to help get ideas and thoughts flowing to help Fred decide. Practicing with what we'll race is good! So good job guys, keep it coming...