How can I make my Miata faster?!?

I just got a '90 Miata and I'm just curious to see what I could do to make it faster. If it's even worth putting money into that is! Thanks

Tough question. 1990's had 1.6L engines that were reasonable performers and very durable (other than crankshaft key problems that let the vibration dampener wobble). Cold air intake (eBay vendors but AEM is good), header, performance muffler would be a sensible start. The ignition timing is adjustable on 1990 - 1997 cars. Set it to 14 degrees BTDC. Great handling cars! They don't need a lot more power to really get the pleasure out of them.

I have a non-stock 1999 Miata that I enjoy daily.

At the expensive end, the motor will handle boost, so forced induction is popular.

At the cheap end, advance the timing & loose weight.

OK, if really want to boost your Miata's power and don't mind spending some money (aprox $5,000), I recently found a company online that will fix you up. Its called Monster Miata. They will install a 5.0L V8 and make it both street driver and street racer. They also sell DIY kits. Check it out! and no I don't work for them, I'm just impressed with the possibilities.
Hope this helps.