(Busa Dreamin @ Nov. 30 2006,07:42) I called and spoke with someone at Factory Pro, asked him about the claims of +6 to +8 HP. I said that sounds like a big claim everything I had read before about Velocity Stacks said you would only get a few HP (2-3). He said they tested different size stacks on a Dyno until they found what works best.
I would like to from someone that used them though.
Just a note there claim is +6 to +8 in the upper midrange.