Problem 1.
During the Italian league, Pietsch suggested some solutions. The Mtx5 is subject to change breakage of the gearbox. The pinion of the second gear, the gear touches plastic. Necessary to reduce the thickness of the pinion # 2 to the lathe. You could put a thickness of 0.3 mm between the first and second gears in plastic. According to Pietsch, however, is not good solution. The main problem is the brakes. During braking the frame is subject to large bending forward. For optimal performance, everything must remain so. Pietsch normally does not use the brake ..... it is set to "soft".during a crash, the gears are subject to breakage. The introduction of a change you can limit or eliminate the problem, even if you lose 1 Performance of tithing. Just put a "carbon rod" between retrotrenoe the radio plate (roll).
Problem 2.
The engine mounts are low for some motors, like the SIRIO. The motor is too close to the frame .... and this involves the breaking of the casing. There are optional exceeding 1 mm.