Check out this page POWROLL
. It looks like it has everything you are looking for. It looks like you can get up to 430cc just off the stroke. Then I guess you could go extra big cc if you get the big bore kit too. I am wonder if it works like this..
Stock 350cc increases to 430cc with the stroke, so 80cc increase.
Big Bore kit is 393cc, wonder if that stroked crank would increase that too 473cc?
I think it is worth shooting them people an email and asking.
BB kit + machine work to stroke + race cam = $810
Plus you would wanna get some quality internals too, springs/gaskets etc..
Then a big azz carb too. We are talking about $1,000.
Dude, just thinking about that much power on a three wheeler scares me!
Sounds awesome though. I wonder if it would be able to defeat those fast 450cc quads out there?
As far at the dual exhaust, I have no clue. I imagine trial and error, or better yet finding a place that could dyno your engine for you.