the e30 m20 (6 cyl) is a good car. You can get them loaded up nicely, and they are pretty quick. They are 170 hp. The engine is very well engineered, and lasts a long time. There is lots you can do with them. If you get tired of the performance, converting to a m50 (1992-1995 325 motor) is reletively easy, and yields a nice power increase.
<img src='http://www.bmw-forums.com/forum/uploads/post-4-1075405310.jpg' border='0' alt='user posted image' />
1987 325is body
1995 325 motor
Performance upgrades: Genie headers, BMP cams, full custom exhaust (dual 2 1/4", mandrel bent, stainless), K&N filter
Other upgrades: Sony deck, Sony 10-disc changer, sony 6x9's, high end alarm (keyless entry, motion sensors, logic sensor, etc.)