You’re right they come with open holes. On another BBC Forum I have read the following messages”
Confusing. No plugs, 1 plug, blowouts, etc.?????????
Maybe someones tried it on a Jaguar or a Cougar???
1. ” I plugged all 3 holes in prop cuz I know everyone says the SHO motors want a ventless prop. She would breakover at 3100 rpms on holeshot”
2 ” On my fury I have to leave one large plug in because of blowout.”
3.”. I spent countless hours dialing in my old p4 and the 25, no plugs, flush JP, load balanced, and fuel half tanks across all three and you should have a 69-71 mph boat. this was in Mobile, Al