I wonder where they get the horsepower estimates for each "stage" of portwork. If it depends on other engine modifications, what other modifications are they talking about? Methinks a turbo. Considering the head is half the engine and there's not much else you can do to the rest of the engine aside from a different CR piston, I/H/E, I would highly doubt you see those kinds of gains from that sort of thing.

Not to beat a dead horse, but given the stories about simple things like EGR block-off plates being fucked up and that turbo kit that's being posted all over the place, I can safely say this is not the shop I would want taking a die-grinder to my head. No way in hell.

If you've got I/H/E/UDP done, the next step is to get inside the engine. Realize that any money you invest at this next level is monto sell it. I would only get this sort of shit done if you are dead-set on keeping the car long term.

As for what sort of numbers to expect, expect to have to go to a shop, strap that bitch to a dyno and report back.