Well I googled the hyper .21 8 port w/boost, and I found it for $125. I'm about to buy a hyper 7 and I was thinking about buying the .21 w/boost and mounting it on the hyper 7 and putting the stock .21 on my 1/10 stadium truck. $125 is a pretty good price IMO if it's got the power I think it does. However I don't fully understand how the "boost" works. I noticed in the pictures it has what looks to be a fuel line of some sort running from the back of the engine to the carb. To me it almost seems like it's supposed to work like a turbo of some sort, possibly using the back pressure from the exhaust. I don't know, ofna doesn't give too much of a description.