Rich I worked on a project engine for DCAE... it was 2 teams of engineers that would build a race car/truck and we ended up drilling coolant holes in the heads.. holes were in the block... we tried a few different sizes to get the flow and cooling right... that ended up in the production engine(I believe it was a 3.5L but I dont recall).. made a big difference on the dyno when we were buzzing it hard and made more power