I've nothing really to contribute to the pre-existing discussion - only to say I think what you guys are doing is great. I really wanted to Turbo my car, and I've almost reached the $5k mark saved, but it seems like a lot of hassle when I could just go the Factory-HPD route.
Basically, I'm jealous as hell of all your guys' knowledge on the topic. Best of luck with the continued build. My dreams of owning an uncommon car with that iconic "Pssshhhhhh" sound will have to wait.