All these years later, and the best bang-for-buck mod is still the PI head swap. You can find everything you need for the kit in the $300 range these days (heads, cams, intake, gaskets, bolts). The full headswap is worth over 50 horsepower. Those mods plus an offroad mid-pipe and tuner/timing adjuster will put you north of 260 rwhp, which will be a very good running car and a HUGE difference over stock. If you had the extra money to spend and were only planning on a mild naturally aspirated build, I'd throw a set of cams in at the same time, which should bump the power up close to 300 rwhp.
If you were wanting to do a big, forced induction build later down the road, I'd look into a complete PI motor swap. A little more money than just a head swap ($700ish local to me), but keeps the compression lower for a blower.
There's always the tried-and-true gear swap, too. It will feel and drive like a completely different animal. But, in my experience, by the time you add the cost of the gears, diff rebuild, bearings, seals, fluid, and labor, the actual performance increase (as in how much faster it is at the track) of a gear swap is not worth it for a cheap, mild build. I'd spend the money elsewhere first.
Is your car an auto or manual?
