Mark...you're killin' me...LOL...I deffinetely DON'T know everything!!.BUT, I do know, that the vent plugs don't have anything to do with "drag" or pulling to one side. They are designed to do one thing,..and they work great!!
What do they do?:...They allow exhaust gasses to escape faster, out the sides of the hub, and thru it vs. JUST thru the hub. This allows the prop to spin faster during your hole shot from the increased air surrounding the prop (exhaust bubbles)...the inreased RPM's will give you a better holeshot, getting a heavy bass boat or ski boat w/skier up on plane faster. After the boat is on plane, the exhaust will then go out the rear of the prop hub and the vent holes are no longer used. The plugs are available in 3 different styles,....large holes..smaller holes and solid.
Most of the larger props that are used on 200-225's come with the larger holed plugs. they can be removed with a screw driver and pushed back in with your thumb (they're slightly recessed into the hub so you need a tool to remove them). By experimenting with the plugs by adding or removing them you can make a world of difference in your boats performance. On my 901 I have 1 vent plug removed.
I tried it with all 3 plugs in, and I had a horrible hole shot,....the boat was a pig with a full load and it was working hard to get up and on plane. I removed one plug and noticed a HUGE difference immediately....i had a much, much better holeshot. I figured...if one plug out made that much difference,...what would 2 out do?? It caused waayy too much cavitation (too much prop slip...too much exhaust escaping) and my hole shot suffered again...so I put one plug back in, and it's fine.....it's amazing what a difference that venting can do.....Kenny's going to have to experiment too,..but my best guess is he'll get the best overall performance with 1 plug out...just a guess though!
Have fun man!! Spring's comin'!!!
Mac