It's hard finding a definitive word on these heads? We just had one member chimed in and say that they worked great but yet sold the car relatively soon after that. Also we've had engine builders say they haven't had too much trouble with them as well. And then of course we're going to hear definitely without question the old you get what you pay for. I called Speedmaster direct yesterday and they quoted me some damn near Black Friday prices on a set of bear heads and the same kind of deal on a set of loaded CNC heads. I'm Dreaming right now anyways as I'm still thinking of saving the money for Black Friday kind of sale. But definitely trying to get all my ducks in a row now. The first two machine shops I called about the bear heads and maybe loading my stuff up into them said first off my valves probably aren't long enough or short enough or something for the aluminum heads? also one of them said they're known to drop their seats as well and quoted me something like $800 for new seats and guides? LOL on $500 heads! I have a hard time thinking that they would CNC port a set of heads and not pay any attention to the valve guides or seats? Then we get into the whole have to do the same thing to the Edelbrock for more? And if anybody does have them I'd be extremely interested to know how much machine work you had to put into them cost-wise and also how did perform and also longevity? I really can't think of any disaster stories that I've heard of? I've heard of one disaster story about some big block heads. Anyways I would sure appreciate anybody who has some real life experience with these. I'd like to either put them on my list or permanently scratch them off. I thought of all kinds of directions I'd like to go to meet my goals and it seems like a set of aluminum heads would really get me there... As always thank you for your time and experience..