Welcome and congrats..
I would not recommend turbo due to the higher millage on the engine. Staying NA will save you alot of problems with reliablity issues. MP3's (and proteges in general) seem to have quite reliable engines. There are a good amount of people that are over 150,000 miles and even some with 200,000. I am right around the same mileage as you and have had no major problems with the car. The only thing that needed to be replaced were the spark plugs and coils. If you ever get a check engine light with a misfire issue then it is very likely it is the coils going bad, many proteges over 100k seem to have this problem but luckily it is a pretty cheap peice. And in case something major breaks on the engine it is fairly cheap to source a used one and is not too difficult to install.
As far as performance there there are alot of things to choose from, but the best mod for the $$ are ones that increase driving feel and response. Unless you turbo the car you need to accept that this car is not made for drag racing. It is a drivers car, which means it is very responsive and crisp in how it handles. The thing I would recommend as a first mod would be a short shifter and bushings for the shifter assembly.