Ok, I've gotten three answers to my question from prop and motor "experts". I have a 2005 Ranger Z21 with a Yamaha 250HPDI. I have a Vmax 25t1 on it and it performs well. I needed a good spare so I found a Tempest plus 25p. It has no vent plugs and it blows out while getting on plane. I was told three different remedies. 1. All solid plugs to start 2. All large plugs 3. All medium plugs. I have three solid plugs I just bought. I'm looking for a good holeshot and staying on plane at slower speeds.