you can basically only spice up a D series, not really get big improvements. Like a pm3 usdm d15b7 piston, which ups your compression pretty well to 12.2:1 which your stock p2p would go nuts over. The only way to even see gains is to change to obd1, and then tune it. But its all in what you want. You can do it the cheap way and see a little bit of power increase. but probably still gonna be around stock b16 power.
Fun, but not fast. But at the same time its better than what you got.