Ok, I guess I could make a pressure chamber form plexiglass. I do not have access to nitrogen gas, but I do have some argon gas tanks. I think that the main purpose for an inert gas in certain pressure in those pressure tanks, is because the gas allows the spark plugs to ionize the surrounding space better and thus make the spark brighter. I can test this with argon and see what the difference is. If there wont be any visual difference, I will make some tests with the diesel generator. If this also wont provide any positive results, then we can clearly say, that those pulstar plugs are worth nothing and there is no point in spending money on them.
Thanks.