The easiest way to make power is making the engine breath. Change stock exhaust with simple aftermarket catback and headers (reduces back pressure). Cold air intake is also a must. These are the first things to do otherwise the stock intake/exhaust system will be limiting you. That done, I would then drop in a new mild camshaft with added duration and lift. You can expect up to 20-25HP with these mods. I would be a liar telling you to expect more. Don't forget there is no replacement for displacement so that 1.6liter has its limitation. To improve handling, install low profile tires with added width (don't go to wide, otherwise it will slow you down) Add 1 or 2 centimeter of width. There is no limitation to reduce wall height but the more you do, the less comfortable your ride will be but better the handling. Try to keep everything balanced. Have fun with the car.