First, on the B64 the kit steering geometry is terrible (dull and slow in the corners), so I run the Type 1 or Type 3 Schelle steering arms. Type 1 if there is lots of 180s, Type 3 if there is smooth sweeping turns. With either of these, the front top deck makes the car more predictable, less likely to hook in turns...it just carrys a nice arc. You have to swap the steering arms to get any real steering from the 4wd.

For the rear top deck, it really frees up the car, so you have to dial in some more rear grip softening the suspension since the chassis is more rigid.... BUT you can carry more overall speed through turns.