You can't go wrong with either car. However, the R40 weighs in much more than the MTX-3 and unless you get the Japanese 2004-Spec, you will have to spend a good bit on aftermarket hop-ups to lighten the car (my R40 is 165g heavier than my stock MTX-3 which is not the prospec version). For the money, get the MTX-3 Prospec kit because the amount of the hop-ups in the kit are worth it.
It's not what you know; it's what you can prove.
The only thing that is for sure is that nothing is for sure!!!
The needs of the many outweigh the needs of the few, or the one.
There are 2 things in life that are infinite: the universe and stupidity.