I remember very well when the 4 was released.
I had a fully loaded MTX3 and I couldn't imagine the 4 to be that much faster.
I decided to stick with the 3, until the first MTX4 showed up at the Sugar Bowl in Atlanta.
I think it was Uriah who drove it, and he was a lap faster in qualifying. With the same cars we were a pretty even match.

He let me test drive the 4 and a week later I had one too.

That's what I always loved about Mugen. When they release a new car, you can be pretty sure, that it will clearly out-perform it's predecessor.

I spoke to Mugen at the toy fair yesterday and they are aiming for mid summer as release date for the MTX5.