I was just reading up on SCCA class rules yesterday...
Enlarging that upper hole kicks you all the way out of Solo Street Prepared, IIRC (even though camber plates are allowed.)
I don't know about road racing, and of course it all depends on the sanctioning org. (SCCA, vs NASA, vs whoever)
Might be worth considering. Don't want to make a racing product that's illegal for all the likely Contour racing series.