The GTSpec parts are designed to reduce chassis flex. During normal street driving, your chassis flex will not be severe enough (or severe at all) for a GTSpec part to make any sort of difference. In fact, it adds weight. The best performance mod you can do are a few since you don't autocross and you don't drag. Who the hell drag races front wheel drive cars anyway?
1) Remove your spare tire, jack, and any tools associated with that.
2) Remove your carpets. Make sure to clean your bottom carpets once a month at least to prevent spots and permanent damage!
3) Remove your ski rack.
4) Remove anything else you're not using from your car.
The first two alone are worth 50, 60 pounds of weight. That's going to mean better acceleration and better fuel economy and will cost you nothing. The ski rack increases aerodynamic resistance (drag), especially at highway speeds, and removing it will save fuel. Fourth is just a further improvement on the first 2.
For street driving, though, anything that produces more torque is preferable since you're driving at 1500-3000 RPM at all times. Ride quality is also key since a Protege5 is a daily driver.
A cold air intake would be a find upgrade as long as you fit it with an air-bypass valve to prevent hydrolocking your engine. It's not fun. Ask me how I know. It adds almost no low-end power but it's the cheapest go-fast bit available for our cars. In general, focus on light weight, torque, and most of all, comfort. Our cars are fat pigs that could really be lightened significantly. Keep that in mind.