If the fuel pump is good, you can slap in a test pipe, fill it full of race gas and give it as much boost as you you want.
Seriously, though, no matter what chip is in it, the car won't be faster than mid 13's on straight pump gas, no matter how much boost you put in it.
Chips that allow 17-18 psi of boost on pump gas do so by cutting back on the timing so it's kind of a wash as far as performance is concerned, especially if its a stock turbo, stock air cleaner, stock exhaust car.
With a Turbo Buick, you need to reduce backpressure, increase intake flow, cool the charge temperature and Increase octane (to allow more boost) to go faster, then make it hook to be quicker.