1990 Cadillac Sedan DeVille
Previous owners (forgive me if i don't use full names, the internet is, after all, EVIL!)
Dean D. - My grandfather on my mother's side. owned since new, as far as i know
Walter K. - My dad. Owned approx. 2000-2004, until i stole it from him :P
Daniel K. - Me! 2004-present
That's the whole lineage of the Caddy. People crack jokes calling it a family heirloom, as though it's some classic car. Truth is, in 18 years it's gone through three generations - talk about depreciated value!
Performance: (and i use that term loosely in this case)
Magnaflow catalytic converter - $175 installed
Flowmaster dual-exit muffler (stock replacement on V8 Camaros) - $dont remember
MSD ignition - $FREE (until my brother realizes i stole it LOL)
All of this seems to have helped gas mileage, though i don't remember what i got before. Average seems to be around 23 highway and 18 or so city. Might be optimistic on city MPG though, as i've mostly been interested in highway MPG. Exhaust provides a decent sound, which is surprising, since these engines usually sound like A$$ with performance exhaust on them. Exhaust tips stick out just barely from under the rear bumper. Very low-key, no chrome tips, etc. Just the way i like it!
Stereo: (for blasting Metallica at the Homies)
Pyle "annoyingPOS" 1.5DIN AM/FM/CD/Casette (Going to EBAY if i ever get the Pioneer DEH-P77DH)
Pioneer 5-way 6x9's in rear - FREEBIE (courtesy of your local retard who got his car impounded)
Pioneer 4" in dash - FREEBIE (see above)
BOLT (AKA El-Cheapo) 350 Watt Amp
Bolt 12" subwoofers in sealed box
This is really cool, and fits into the low-key thing i like. You can hear excellent quality sound, semi-heart-thumping bass (though not as good as some), and turn it up plenty loud, and still not hear any bass on the outside. Sweet, since i can't stand the ground-thumping, look-at-me, my-parents-didn't-love-me-enough stereos that every retard seems to have.
Repairs: things that have gone wrong :(
Water pump - $300 or so (had it done, i don't dare go too far into these engines!)
Front clip (Yea, i wrecked it because i'm stupid LOL) - $500
Cleaned EGR tubes to fix rough-idle - FREE (Used .45 cal and 9mm gun cleaning brushes)
Replaced 3 or 4 injectors (went a little heavy on the fuel injector cleaner) - $~45 (Courtesy of local wrecking yard. Got all 8 and picked out 4 good ones. Got FPR too just in case)
Heater core - $~45 (Did it myself. Surprisingly not all that hard on these cars)
Motor mounts (all of them were shot!) - $don't remember
That is all I can think of right now as far as repairs. Something goes wrong, I try to fix it as soon as possible before it causes anything else. I can't remember how many exhaust donuts I replaced before a mechanic told me the catalytic converter was plugged, which made them keep blowing.
Updates: (a.k.a. Repairs, cont'd)
Water Pump again: $45 & 3 hours. Was able to do it myself by jacking up the front (passenger side) of the engine. this gives plenty of clearance to replace it.
Blower motor: $~50. Needed the wheel too. Had to lower the front of the engine to get clearance by removing the front engine cradle bolts. Also removed the EGR solenoid to get that extra inch i needed to remove the blower.

This is the Caddy in it's semi-permanent parking spot, Next to the driveway in a mud hole.

This is in the snow, near Lake Arrowhead, CA, in winter 2006 i think. We lived in SoCal at the time, and didn't see snow very often.

This is the best pic i have of the exhaust. The flowmaster muffler is the same one that you would buy if you had a V8 Camaro. It would be a direct swap for that car, but on these, the exhaust hangar had to be moved in a bit (toward the center of the car) and another one added for the other tailpipe.

Pic showing the 4.5l V8 in all its glory. If you click on the pic, you can see the unibody damage around the radiator cover. That comes from rear-ending a 'Vette and pushing it under the back of a buick. That's right, i said under! DOH!

MSD ignition. The wires are zip-tied to the radiator hose on the underside to hide them. Have yet to figure out if this little red box is actually doing any good.
Just a quick little shout out to the guys at www.cadillacforums.com. You guys rock!