MellowYelloW, I just bought some Bassett inserts he calls hypos which have steel wool in them. He said that very little power is lost. He's coming out with some new kind in about a month that will have some device in them that will open up at higher rpm's, but he thought the ones available now would be best for my application (v-drive). By the way, they wouldn't go in all the way with the bolt hole at the bottom, but rotated 90 degrees they would, so I drilled a new hole in each one. Guess my old headers aren't round or something.