I agree with KaiserBill. It's a complex recipe. I've often wondered what type of hp/torque gains you'd get with just the larger injectors that come with these forced induction kits together with premium gas and an aggressive calibration. Let's put that on the dyno and pull without boost. People seem to focus on boost and PSI. But, as we all agree, the compressor is merely a means to an end. The end being a desired air/fuel charge. Again, I'm no expert but having built my fair share of naturally aspirated engines I know there are plenty of gains to be found in just helping the motor breathe better. The vacuum of the piston dropping on intake is not always met with an efficient air/fuel charge. Port size, runner design, valve size, cam degree, lift, duration and so on all affect whether the air/fuel charge snaps into the cylinder or slugs into it. If you've ever set cam degree then you know you can get a better air/fuel charge by delaying the opening of the intake valve a bit and causing the piston drop to create vacuum. When the valve opens the "rush" generates velocity and fills the cylinder better than if intake valve were to open right at TDC and the charge were just drawn into the cylinder. But don't wait too long or the vacuum can draw the intake valve open and cause havoc. Also, don't create too much vacuum and encourage power loss. And, of course, one cam degree doesn't serve all RPMs well. Nor does one anything. And so we have Variable Valve Timing, four valves per cylinder in some engines, unequal length intake runners, dual plane manifolds and so on. We have myriad options to play with.

The point here is unless you know how each calibration table is set up at a given RPM you just can't know what's going on inside the cylinder and what the HP/torque numbers will (or should) be. I'd approach it by defining what I want to achieve. Max torque at 2,800 rpm. Max HP at 5,500 rpm. Killer low end torque. Screamer peaking near redline. Build to your definition and don't worry about what others are saying they can do.

Of course, all that said (rambled) I think RIPP could be "a bit off" in their claim unless, of course, the thing is tuned just perfectly and you wouldn't really need any boost to get the gain with the larger injectors, cams timed right, ignition spot on and high octane fuel.