What are some cheap ways to make my 88 crx faster?

I've got around $200-400. What can I install to make it faster? What does installing pistons do? Or cams. Oh yeah it's a sohc non vtec. I used to have a hatch back with a sohc non vtec stock motor and I bought a turbo kit for 350 and all I had to do is install it and switch my old ecu with one the guy had set up for turbos so it will run smoother, no other modifications.it was fast, just enough speed for me. the motor I got in the crx is stock and a little older than the last one I had with the turbo. Would it be safe to slap on a tubo on that motor? If not what parts will help it get up to speed? Also it already has a full exhaust system.