I agree, I wouldn't buy it either, 5 bucks now to try it out, potentially costing you hundreds in future repairs. Of course they going to make it sound good. If he gets 5 bucks from everyone that was curious and wants to try the product. He is making big profit. Now does it actually work? it could maybe give you a small increase but probably not near 20hp. but does he care??? Well he is making the money, and if it fucks you over in the future it aint' his problem...