If you're looking for power, you're best off doing a motor swap. The best fun that can be had for Protege on a budget is in suspension upgrades. Coming from a 1.6 Protege owner with intake and exhaust, and suspension mods, the car is far more fun around the corners than in a line. If I had the money, I would swap in the 2.0L, forge the internals, and turbo it.