Now that we've thoroughly hijacked a perfectly good golf cart thread...
I think that there are a bunch of issues commingled here:
1. A number of GP cars were dropped into HP, by and large they are heavier, more powerful and faster in a straight line.
2. Runoffs moved to Road America, a very fast track.
Thus I think it is fair to say that - at RA and thus for purposes of the National chamionships - the existing (as of 2008 or so) HP cars are generally disadvantaged compared to the ex GP cars. (This is a generality with exceptions.) This applies to the 1.6L VWs as well as the Spridgets and others.
But - and it is a big but - for the 90% of us HP Prod racers who are realistically never going to be on the Runoffs podium, the Spridget, 1.6L VW and some other cars are very competitive on the more average type tracks that most races happen on. My purpose in belaboring this is to try to make the point that - on most events at most tracks - there are a wide range of HP cars that are fun and competitive.
Too much noise about unfair advantages of a few cars - while valid at the Runoffs level IMO, largely because of the venue - can make the class seem unattractive to outsiders and thus seal its doom. The fact is - IMO - that the 1.6L VWs and 1275LP Sprites make good, practical, fun and competitive race cars at many or even most events. I'm having a blast racing my VW Scirocco at Summit Point, trying to figure out how to beat a Sprite that is nipping at the lap record! And being chased by a couple of other continuously improving Sprites....