There we a few big blocks (jets) I don't think anyone with an OB raced them.
I did see the 2 big blocks race each other, one was blown and sounded ok but was not a race boat. Go to Havasu Barney and you can see some photos of the OB's. Barney got there late and the BB's were gone so no photos. I'll post my photos later, I might have a photo of the BB's.