Well if you look at it that way, the old 2 stroke 500cc GP bikes were producing 180+ hp. So if extrapolate that up to 5.4lt (ish) thats over 900bhp....(i think, maths has never been my strong point)
But again back to the topic. Mazda have only continued to use and develop the rotary engine for marketing purposes, and maybe a touch of engineering prowess. Engineers can be funny like that sometimes, they're a weird bunch.
Slightly off topic, but does that new Furai use a Wankel engine ? will check..[quick edit] yes it does, it produces 450bhp, not sure of the capacity though, more checking needed..