I have been using the OS 70 Ultimate and it has very high compression, in the ground I get pre ignition, in the air no pre ignition, meaning I am right on the limit as far compression ratio is concern. The OS F plug last for about 100..120 flights, after 70 flights I can feel the power going a bit down til I have to replace it for good.
Any way, it is a new plug for our engines. If it is going to be better or worse I do not know...I am just sharing the information.
As far as I can tell Enya plugs for 2S are superior then other brands I have tested OS, T.Bolt, Fox, Fireball, McCoy.. So I will certaingly try one on my 4S engine.
I bet it will last longer then other plugs and at the end it will cost less.
Martin