If you run the plug from the kit, and you use some nitro in your fuel, that should not be a problem.
You don't know if your engine is set too lean. Try turn the HSN ½ turn out, and run your car. My guess is it will run rather rich now (4-stroke). If it still screams at wide open throttle (WOT), you should turn the HSN another ½ turn out. The 4-stroke mode is a perfect startpoint, because you will not be able to adjust an engine, if its too hot (lean).
Take a look at the videos from the Tuning Bible thread: