from the Medial Pro site:
Engine 3,5cc especially adapted to models 1/8off road. Originally tuned by JP Racing. This monster has qualities of exploitation, performance and autonomy out of the commun run...!! Long stroke 5 ports, reinforced camrod type "R", "Turbo" plug insert, special long off road head, Hardblack treated , ventilated crankcase , High speed ball bearings, Carb with thermic insert adjustable choke tube, Hardblack treated super light crankshaft A must!!
i have the M2K, which is its older predecessor. The hard black crank (more durable) with putty filling bring fuel in more efficiently and quickly and make it scream. Not much, if any, work on the sleeve and piston. You could drop a JP B5 mod sleeve in there if you have an itch.