I had the same issue with the top deck with a Tekin motor, had to shave the top deck back. I also found I have to remove the motor to tighten pinion grub screws as the gap between the two halves of the top deck is very close together, the left side being over the top of the grub screw.
The steering servo is a bit of a fiddle, could they have not moved it out or back a little bit to clear the steering posts?
Other than those niggles, very impressed with the quality of the kit.
Xray XB4 | Kyosho RB6 | Kyosho Rudebits DB2