Having one fitted to my car next monday, went on the rollers last weekend, got 225bhp at the wheels but having same problem, getting big punch of power then its dropping off. Was also told and shown that the boost controller can help bring the boost in smoother eliminated that massive kick, which in turn will help pro-long the life of the gearbox.
Am also having it set-up with different saved settings, i.e 1 button will run 7psi for motorway cruising, button 2 can be 1 bar, for a bit more fun, and button 3 for the 20+psi mad nutter mode, lol