Right there with you Rageworks, I have broken all my Go's in on a P3 then chnaged to the P4 after the first couple of litres. The P3 is great for getting a good strong idle very easily however the P4 seems a bit better after its broken in and you can get a little bit better power from it on the colder plugs. In really hot conditions running on 30% I have gone to a P6 before as well but as you said, you have to be right on the ball to get the tune spot on and a small variance will yield poor results or flame outs. I love my Go motors however I have to say I am not a fan of the Go Plugs as I found went through them rather quick, where I seem to get 3-4 litres (1 US Gallon) on one plug with the OS plugs. The LRP #6 (about a P4-5) plugs aren't bad, I just had a bad run for a little bit (maybe it was just the batch) and went straight back to OS/Ninja plugs (same plug, different brand). O'Donnell plugs aren't common here in Australia so I can't comment really though from what I have read, they have been good.

With Go motors, the most common tuning problem I have found is that people tend to have a large idle gap and compensate this with a rich bottom end, with the net result of power not being up to scratch and blowing of plugs, watch this one. Pull the air filter, set you idle gap to about .7mm and tune the LSN from there and you should be giggling.