Roger, thats because they are the current hot broadhead. Wait a while and you can get the next hottest broadhead. In my limited experience after squaring my arrow shafts and inserts thunderheads, wasp mechanicals and wasp cam locks are the closest. Current thinking is to use a smaller broadhead for better flight. The wasps mechanicals are the closest and the cam locks are a close second or the same. Thunderheads work better in my compound than my xbow, donno why but its not enough to make a difference shooting at deer.
Hows that BPS shooting?