Here's my 17.5 B6 laydown setup, I would recommend shocks forward for more rotation in the tight turns (but a little harder to drive) and shocks and tower on the rear of the arms for the easy to drive setup. When you run the shocks and tower forward on dirt, remember to move the rear wing, it needs a 10mm gap to the tower so you have it in the same position relative to the axle.

Source:

K. Wenger