What you are talking is what I've wanted to do for a few years now. You want ridiculous power everywhere out of a 2 stroke. I think it can be done but at a whole lottah time and money invested.
I'm talking totally off my head now but I do have some 'hands on' experience here with my 400 single blaster. I made a trail pipe for it using a DG YZ400 dirtbike pipe. I ended up adding a few inches to the headpipe- just to make it fit the chassis. What I ended up with was a powerband that pulled the wheels up litterly right of idle in the first 4 gears. The problem is it ended at about 5000 rpm. I had the motor re-ported and it still didn't make a difference. The pipe was just all wrong.
I picture a 4mil DM having great torque because of it's shear size but then ripping your arms out of socket when the powerband really hits.
A powervalve WOULD help a lil but the pipe will aways be holding you back.
If you could have an adjustable pipe like the 350cc hydro boat racers use, a powervalve, and a big motor you could prolly get what you want but like I said that would probably never happen.
Here's a vid of an adjustable headpipe incase someone is wondering.
Here's a vid of my blaster with a too long headpipe