i can not say that i have used any other chips other than the Jim C. chip, but i can say that i do love the Jim C. chip. It actually smoothed out my idle, and did add a little kick to my 88 535is. We also instlled a Jim C. chip in my friend's M6 and using a G-Tech we got 6.4 sec. 0-60 without the chip and with the chip he was running 6.01 sec. The horsepower reading jumped up to 280 from 256 according to G-Tech. i can't complain, i would definetly recomend the Jim C. I have a 1986 535i with 170k miles on it. I just got a major tune-up and it runs great. Yet I want some more performance out of it. Which is the best chip available for a car with this many miles? I don't want to affect reliablity, but want the most I can get out of my car w/o hurting it! I don't want to do any engine mods now...I just want a GOOD chip for it. Your opinions will be helpful!