Pre-Project: You crazy mo'fo..

[Niall]

Tbh for the cost of a piggyback ECU like your suggesting, it wouldn't cost much more to go completely standalone and then the worlds your oyster in terms of engine mods

I reckon it still might drive with the boost as low as possible but as said, it would be utter crap but if it means you can get there, it might be an idea.
My engine is sold Ginge otherwise I would offer it to you but then again, if your boosting it, it might be worth getting a second hand one and rebuilding the bottom end anyway. I know I did mine but the bores weren't in brilliant condition because of the way the engine had been treated previously.