I remember at last years rules meeting this was brought up (also the previous year
) but it didn't really go anywhere. On one side of the room were traditionalists who didn't want bike engines in cars cuz it just aint natural and on the other side were those who said racing is racing and let the chips fall where they may. The stand off was broken when sample wording was bounced around and it proved impossible to nail down. Damn them honda 600 cars that came with modified m/c engines from the factory!
As Sumner said, I run an "H" in a car class and am not really concerned about a busa powered car running over me. If one did outrun me then it would be more a statement about me then about the busa. I think "I" engines and smaller do give a natural advantage to the bike engines, "H" would be a toss up and "G" class would go to the car engines.
A good blown "H" needs to make 500+ continuous, reliable HP at the wheels and thats pretty average for most busas and Honda car engines.
A good blown "G" needs to make 750+ continuous, reliable HP at the wheels and thats pretty much out of reach for a busa. At some point you are going to be blowing the cases apart but a reasonably well built K20 Honda can do that all day long with off the shelf parts.
Personally, I am a fan of innovation and loved seeing the busa engine in the back of the rear engined modified roadster. But I also understand that it does upset a few people. Too that I just say don't worry, they wont be running against a AA record anytime soon (or even an E, D, C, B or A for that matter).