I have Italian GS40s with divided transfer ports and non-divided. I have not been able to see a clear trend as to which is better, I've had "strong" and "less strong" specimens of each. Was not aware there was a "cheater" GS40 crank? Thought all GS40 cranks were the same?? Exhaust makes a big difference- the "Eco" muffler really strangles the engine, the swing are much better. The "standard" and "silent" swings seem to be about the same, the silent is a bit heavier but with the new weight rules that shouldn't matter much. Have never run a Chinese GS40 to compare with my Italian.

The TTPRO 40 has at least as many issues- aside from the breaking muffler thru-bolts and general difficulty of getting parts like that oh-too-easily broken off NVA, there's versions with beveled rods and square rods, ones with bigger crank gas passages, and of course the dreadful rear bearings. I don't really see how the TTPRO is much more "stable" than the GS40, and parts availability is a drag.

I've heard "tribal knowledge" that the TTPRO is the "only" 424 engine but have never seen that in any official way. I have heard some clubs allow the GS40 as well. I, too, would like to know what the real story is, are both engines allowed? Is the static rpm limit the "new" format, with any stock, under $120 .40? Hope this can be cleared up!