Wow, a whole stack of ignorant people today...
You do realize your Galant weighs over twice what a Geo Metro does, right?
How do you know it was a 3 cyl turbo? the Metros didnt' have 3 cuyl engies. That was the earlier Chevy Sprint (bothe Chevy Sprint and teh later Geo Metro were rebadged Suzuki Swift/Cultus models). The earler Chevy Sprint and Suzuki Cultus were available from the factory with 3 cyl, intercooled, turbo charged enignes. The later geo Metros didn't have any performance vrsion, but the identical Suzuki Swift was avaiaolble in a GTi form, with a DOHC 1.3 liter engine that made 100 hp. Doesn't sound like a lot, but the cars weighed less than 1700 lbs, which put the power to weight ratio right up there with your 250 hp car AND they had bettter gearing, which made them quicker than a lot of cars. And the earler 3 cyl turbo cars weighed closer to 1500 lbs
They made excellent road race and rallye cars, so a lot of people raced them and modded them. If you start with a light car, you don't need as much power to be fast. Turbo Suzuki Swifts are all over Australia, with at least 1 400 hp AWD version using the 1.3 liter engine...
Here's the 3 cyl turbo version:
Pretty quick, itself, in stock form.
This is the Swift GTi. I had one identical to this one:
45 mpg, plus a successfull autocross car.