Beer-30 - That is something that I didn't realize. I originally purchased the bullet clamp-ons but when I got them, I decided to return them and go with the bolt-on style. When I went down to exchange them they were out of them but had these. I compared the two....length, inside/outside diameter, etc., but the only diffence I saw was the outside diameter. I wonder how much difference there could be in just that dimension? I am sure the bullets will flow better with the bigger diameter, but is it enough to make a diffence on a motor that will only be in the 500-525 HP range?? I am not sure how much of my boating time will be spent at the WOT range and will I miss a mph or two....probably not. Besides, there were almost half the price of the bullets. I will definately keep in mind though. Thanks for looking out for me.