Let me play the devil's advocate for a moment...
Let's say the ZR1 will beat the ACR or any other comp on the track (Ferrari, Porsche, other $150k cars like the GTS-R). If that is the case, would it not be a better bargain than the $150k that guys are spending on Z06 full blown race prepped cars to win the NASA TT or SCCA crowns (to beat the $150k Porsches)?
Maybe the ACR looks like a bargain now because the perception is that it will win the track duel. Suppose it doesn't? Suppose that Porsche also has a car coming out that will beat it? Suppose the GTS-R also beats it? Then is it such a bargain?
I know that it will be a fun time when a ZR1 and an ACR are head to head, be it at a stoplight or at a green flag. I think that the ZR1 guys are more interested in lining up with Ferraris and Porsches. Satisfy yourself on the 'bargain' mentality if you want, but I say that the Viper needs to put out 650HP in 09!
P.S.-The Ford GT is old news. It hasn't beat anything, and in the future won't beat anything. A classic example of all talk, no podiums.