Again, the noticed differences do not come from the plug shape but more from the shape and volume of the combustion chamber and probably the type of glow wire. In the past I and some others had issues with turbo plugs and I switched to a normal plug w/o any issues and performance loss.

That those plugs can stand up to 60% tells me the engines are normally running on a low compression while our onroad engines are set to the max compression with very cold plugs leaving les space to run more nitro.