I wouldn't say that you can't make any performance mods to it. But in terms of mods that make power your choices are limited because of the engine you run... Swapping to a K-series would make your life more difficult but then you'll have more options in terms of mods.

I would be asking myself how deep my pockets were if I was in your situation. It might be better (cheaper) to sell this car and get yourself something which you can find mods for. Any B series (vtec) or K series.

It doesn't even have to be expensive either, you can find some really nice EK civics which are really good platforms to build on or DC2 Integras. Newer EP civics and DC5 Integras would be more expensive obviously.

You should sit down and see what your budget is and how much you want to spend overall with the car and the build and then go from there. It would also be a good idea to set yourself a power figure to aim for and see what mods can get you there for the money you have budgeted for.

Remember this but:

Cheap + Power = Not reliable
Power + Reliable = Not cheap
Reliable + Cheap = No power