The M/P cars were a few tenths faster, but we usally pulled the crossram in favor of a tunnelram and dominators. There was also extensive port work on the heads that you could not do on Superstock heads and be legal.Along with more overbore and higher compression pistons. Also the M/P cars were gutted and fiberglass doors and trunklids were used. So the cars were much more different than a carb change...