If you run a 24v vr6 in the car, you can get about 230bhp without raising displacement. ON the 12v vr6, its making 230Whp on a high compression 3.1 setup, still with decent engine life.
Trac Racing ran a couple VR6's in world challenge, but the main problem is thier weight, and the 16v 2.0's that are not being run make enough power and are light.
VR6 is a great engine, but its size/weight is a problem that would need to be overcome. There is an Ex-WcT gti vr6 for sale now for $20K, and they can probably drop a 185whp vr6 int for $7500 or so.
I am not sure how much thye would limit th VR6, but you can run a 2.9L, with 288 cams, headwork, custom intake manifolds, headers back, custom ecu, and you are a solid 200whp there.