My passion before that dollhouse was my 2002 Corvette Millennium Yellow coupe. When I purchased it in 2010, it had 2,900 miles on the odometer. Seems a rancher in Abilene, TX bought it for his wife, but she didn't like it. So they parked it in the barn, then finally drove it to a Fort Worth BMW dealer to swap it for a new BMW.
The stock car had a 5.7-liter engine with an advertised 350 hp/350 lb-ft of torque, all measured at the flywheel. Well, once I bought it I made lots of changes. Gutted the interior (and its gray leather) and replaced it with custom "baseball glove brown" leather that I had specially made. At that time I also removed the stock stereo system and replaced with a 900-watt amp, driving a navigation head unit, custom door/cabin speakers (with tweeters mounted in the A pillars), and two 8" subwoofers mounted in the back. Added new gauge faces to match the paint, and similar dash-specific improvements. I did 100% of the interior work myself.
Mechanically, I had a local "wrench" install an A&A supercharger, special "blower" cam, new stall converter, race transmission, race differential, coil-over suspension, beefier sway bars, upgraded rotors/calipers mounted in "plus 2" specially ordered aluminum wheels (built by CCW). Then I added a chin spoiler, side ground effects and a rear lip spoiler - all to keep the car planted at high speeds (i.e. in excess of 175 mph - which the car easily attained). The "as finished" power train dyno'd at 600+ rear wheel hp and 520+ lb-ft of torque, which mathematically converts to around 725 hp at the flywheel. Suffice it to say my 0-60 times improved, although hooking up was always a dicey proposition.
I used to joke that the only thing that remained "stock" on my car was the paint.
Overall, I spent twice as much doing all of these upgrades as I spent on the car's original purchase price. Silly? Sure. Did I get my money back when I sold the car? No. But I knew all of that before I ever started. The process took about 5 years to complete and was tremendous therapy.