Lambda does terrific work, and I'm sure that if he made a 2D 5W light then it's a great light. I wonder what converter he's using. I don't think 2 cells is enough to run a BB750. Maybe the 2D light is another one of the excellent Lambda-ArcMania collaborations.
Anyway, the absolute simplest and cheapest way to make a 4D Mag brighter is just drop in a Xenon bulb, XPR113 or something like that. There are a bunch of threads about it, try a search.
Modding a Mag to a 5W Luxeon light is a fairly significant mod whether there's a step-up converter or not. It's certainly doable though, and it's been done lots of times.