Amazing car. A friend of mine has a Chevy SS that he changed over the exterior to all Holden badges. Gorgeous inside and out. It's a shame they never intended to sell or even market these because they're awesome.
I've heard that if your car needs to run in the dyno with the hood open then the numbers you're putting down are likely artificial (since that's not how cars drive down the road). Make sure that shop isn't just touting good numbers with the hood open. Hold them to the numbers you put out with the hood closed.