Exploit the horsepower glitch in GT2? Info on the net for this was on years ago and well documented, but I can't find anything about it now. It was pretty well documented. What would happen is you had to buy your upgrades (for the engine) a certain way to have the glitch take effect. Eventually you'd have a horsepower boost of about 20% more then you were supposed to. If you downgraded, then you would lose the "extra" power and have to start from scratch.