ZX2 with sports package straight from the factory.
Current Mods:
Resonators removed out of intake with K&N drop-in air filter. Parts of car removed for weight reduction (pieces and bits and brackets from the trunk around the spare tire area. Pieces around dash and inside interior that were not necessary also taken out). Also took out stock stereo deck, 6 cd changer, and brackets as well for weight reduction (aftermarket stereo and speakers actually were lighter! YAY!).
Ford racing underdrive pulley kit installed and A/C removed to free up power from the engine and remove more weight. Same size stock wheels replaced with aftermarket wheels (same offset, size, and less weight) so I could use the same stock tire profile.
A long time ago I did aftermarket suspension and installed GR2 struts, suspension techniques springs to lower the car, stiffen it up and even did energy suspension bushings (this is when I took the car to our local autocross). But driving the car conservatively, over the past several years I actually found that after I stopped doing this that the car's tires were lasting LONGER daily driving with these mods. Makes sense, less body roll, less stress on the suspension, therefore less tire scrubbing = less friction = longer tire life. Can't say I noticed any MPG getting better BUT the tires do last longer now than they did before (Hey that's money savings all in it's own!)
Planned Mods:
I would like to get an OBD-II meter that shows me my miles per gallon and shows me what I'm getting per mile. This would be a nice mod.
My "butt dyno" since these mods says "Cool!" and I've /noticed/ i'm getting better miles per gallon, but I have no scientific way to actually MEASURE what's good and not good.
That's why I'm here
As a personal "Modification" I plan on taking a lot of these wonderful techniques into consideration from "The list". Good stuff.
I've learned your BEST MOD is the WAY you drive your vehicle