bmw started putting the 2.5i engine in the e30's in 87 for the sedans, coupes, and cabrios, and is the most powerful engine you can get in a e30 except for the M3. any 325 with no letters after it, with an 'e', or 'es', has a 2.7L eta engine which makes more tq than a 325i/is but lacks about 50hp and is factory limited to 4500rpm.
I owne a 87' 325 IS and i love it. i have also had very few problems, and it is faster than most of the other cars that are either this old or even early 90's. My car is stock and i would like it to be a little bit faster.[/FONT]
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.