Originally posted by InitialD
Perhaps the OS7 plug is a little hotter and better suited to cure the flaming out problem...
Have you tried playing with engine head shims? Try adding 0.1 mm to the stock 0.3 mm... This would kill a little bottom end and give better top end... Not something you want on a short track.
The other way is to take out the 0.3 mm aluminum shim and just use 0.2 mm shim (2 x 0.1 mm copper shims) and retune engine. Stick witht he 7tf plug. You may get surprising results not to mention a lot more bottom end power. 
But of course this could proove to be worse in terms of idling... Try it out. You won't know till you do it.
Ok in my case all my engines has an extra .1mm shim so I am using 0.4mm and you are right I am the one that has more time (about 4.95 to 5.05 minutes ) compare to the other drivers that have 4.5 minutes.
Now with the 7tf plug and the 0.4mm shim I was having problems
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