Well I always think of power adder classes. Most run tons of NOS or blower, turbos etc. A non siamesed block will not handle the power necessary to be competitive. If the block design was the best then the Prostck hemi block would probably utilize the design. It was designed for cylinder wall cooling for nascar. Nascar engined have to last for 500 miles at high rpm. They are filled with the lightest parts possible. You see fewer prostock motors fail in a weekend than you do in a nascar race. Just put a large turbo on a R5 block and crank up the boost.You will see what I mean.