[rwyler]

I'm fairly new to ecomodding/hypermiling, so bear with me on this. I used to live right next to my job, and drove a big SUV daily (about 4 miles total) and didn't really care about MPG much. Not long ago, I got a new job about 25 miles away from my home so I bought a small fuel efficient car in my price range (cheap) to drive to work and back every day. What I got is a 1986 Honda Civic Si (hatchback). So far, it gets about 30 MPG and will probably get better once the winter weather here clears a bit (less idling, less churning through snow/ice). What I'm wondering is what can I do to improve the FE of this little buzzbox mechanically? I'm a mechanical engineer and a shadetree mechanic so I'm open to doing just about anything, so long as it isn't very expensive or would require the vehicle to be down for weeks.

So far, the only things I can think of are pretty lame and probably won't do much. I was going to:
1. Switch to the lightest synthetic oil in the engine + transmission recommended
2. Pump up the tires to the maximum allowable pressure on the sidewall (44psi)
3. Remove the passenger side mirror
4. Remove the spare tire , jack, and tools from trunk (it's dry rotted anyway and I wouldn't feel safe driving on it, so if I get a flat it's getting towed or I'll have my wife take me and the tire somewhere to get it patched)
5. Remove some of the emissions equipment and tune up the engine (the idle is a bit rough and the throttle response is choppy - I blame the 800 feet of vacuum lines running between all of the emissions stuff).

Here are some dumb/rediculous things I was thinking about:
1. Replacing the transmission with an HF model from a civic or a CRX. The thing runs about 3600 rpms going down the highway at 75, and honestly has more than enough power at this speed, so why not cut that gear ratio and up the fuel mileage?
2. Replacing the wheels with lighter ones + adding LRR tires. This will probably happen when the current tires wear out.
3. Remove rear seat, "extra" trim, insulation, etc.

Are any of these ideas stupid? I'd rather not waste my time/money doing something that won't make much of a difference in the long run. Where could I get my best bang for the buck/effort? I don't want/need 80 MPG, but a noticable improvement would be nice. I understand that my driving habits are the biggest things to change, but what can I do mechanically to get my mileage up? Thanks for the help all, I'll log my mileage before and after any changes to try and validate the effects and possibly help others looking for good info on how to improve their mileage as well.