Why spend money for a kit, risk a OEM or a Tomy, when you can get the full working BitChar-Q (the modified version with IR) for 15 bucks remote included ?
TinyRC has it:
http://www.tinyrc.com/shop/product.php?pid=133
Gif4All in London Airport has it (all the 4 ID)
ToyEast was having it time ago, maybe they will come back !
P.S: As far I can understand from the BitChar-Q, that I belive use same HW then the Kit, the throttle has around 8 step (4FW+4RW), but the signal to the engine isn't progressing continous power with different voltage, but is a square wave with the up time increasing, so with full throttle the square wave is a continuous signale, with minimum throttle the engine recevie some voltage spike.
So the car is far more noisy while half power then in full power !