1. DIYAutoTune.com, 2. TwosRUs.com, 3. columbus.craigslist.org
1. I like going there because, in addition to just selling the Megasquirt, they have technical guides about how people have installed it in different vehicles with different applications.
2. Great store, great service. I don't buy performance parts for the MR2 anymore, but when I did, they were always helpful and had great deals on stuff. I usually just go look there when I am bored.
3. The service on this one can be kind of sketchy (lol). I buy lots of crap on here, including cars and car parts. Most of the time, I just look when I am bored though.