Modding the k20a3 for performance is a waste of time and money imo but people have done it. There are plenty of dudes have that have ran vtec killer setups or even turbo k20a3s you can find them on youtube. I too have a base but I bought it knowing I would use it to learn EVERYTHING about the car and the rsxs in general and then eventually swap in a k24 like everyone should. A year owning the car I have learned anything from replacing the head gasket and timing chain to replacing axles, weather strips, tail lights, carpet, valve adjustment, adjusting the e-brake, rust control,..... there is simply a metric fuck ton to consider if you want this to be YOUR car that you keep for a long long time.
My advice- Put in the time to do your research on here, YouTube and reddit. You'll quickly learn that the k20a3 is fun but slow as fuck and not worth "performance" modding at all. Save your money, make the car running mint, learn how to actually wrench and get some tools for yourself. Once you are experienced, swap it. I'm about to do it and plenty have done it before with the base and you could be no different. GL.