I'm calculating losses at around 15%, based on my experience with new C6 Corvettes with an A6 transmission. Typically dyno around 348HP with a published 400HP.

You must also consider that any dyno pull will have a margin of error of over 1%.
Different makes of dyno's produce somewhat different results.
Consecutive runs can give you variation due to heat soak.

Imperative for me to do the base line as it will give a relationship between published flywheel numbers and actual rear wheel numbers for my engine.

The other power improvement is using the supplied two pipe 2" diameter exhaust with high flow silencers.

I believe 100-150HP is possible depending on the condition of the original engine and how well the dyno tune to obtain optimum air/fuel ratio under boost is performed.

B.J.
Why not do your install with the provided TurboTechnics electronics first..get it running, see how much power you are making and then consider a different type of engine/fuel management ?

Ed A.