I plan on doing the FRPP aluminum DS, but it's hard to associate numbers with it. It doesn't really show on a dyno, but real world driving difference is incredible.
This is what I have planned from now 'till spring:
1. Densecharger
2. Maximum Motosports STB (when actually released for the Bullitt, they're revising the instructions to reflect Bullitt specific items)
3. FRPP Al Driveshaft
Anything else is up to the suggestions I get. So far I've heard MAF meter, and chip.
The downside of doing a chip is it's tuned for the mods you have, so every time a new mod is done, the chip SHOULD be reburnt. This isn't necessary, but the whole point of the chip is to maximize the EEC to the car. If you change the car but not the EEC program, you might as well have not bothered.
When I get the car where I plan on leaving it for while (i.e. no more mods), I'll consider a chip.