I doubt the 5 and 7 ports are different than the 3 ports in regards to squish.

I'm running a turbo button on both my 5 port and my sport 3 port. After about a gallon of break-in using the Adam Drake method, and an additional race weekend, on the 3 port I've gone from the stock .30mm to .21mm. I do use a cooler plug than the OS P3 however. It's the Merlin Glow Plugs EHD #5 turbo. I've got no problems and I'm getting longer run time now.