fordsix.com had all the performance stuff you can get for a six cylinder. One guy has his in the low 14s, and it didn't look that hard to do. But he did a ton of little things to get there, plus the rest of his car is tuned extremely well for it.
That said, certainly have fun. You don't need to swap to a V8 to learn about engines and enjoy your car.
A posi rear with high (numerically) gears, and tranny with a shift kit, nice tires and a decent suspension plus throwing headers, an electric ignition, hi flow filter, nice muffler, aussie cylinder head, maybe an electric fan might get you into the 15s. Several on fordsix.com are indeed running nitrous in scaled amounts, and there is a supercharger avaliable. The aussie cylinder head is supposed to be your best bet though without spending a ton of money and/or putting your engine at risk.