I own an '87 325IS and was thinking about installing a Bavarian power chip. They claim is makes quite a difference. Any words of advise?
I don't know about the Bavarian chip, but aftermarket chips can make a difference / improvement of throttle response, rev limit. For some chips the changes are only evident at wide open throttle, so it depends how you drive the car. Owners' seat-of-the-pants dynos seem to be more impressed than actual HP gains from a chip replacement! The E28 crowd are very impressed with Mark D'sylva's E.A.T. product for the M30 engine: http://www.dsylva-tech.ca/
I have a 91 octane MarkD chip with 19 lb injectors in my car. Very happy, much better than the Dinan chip that was in the car when I purchased it.
In counterpoint, I've had a Dinan chip in my 1987 325i convertible for 10 years. It increased torque noticabably. Note that changing a chip in a 325i retunes the car for 91+ octane gas, which causes most of the power change. Earlier this month I also installed a Dinan chip in my 1991 318i, it smoothed out idle and improved power too. z31maniac and I bantered a little bit about chips in this thread: http://bmwcca.org/forum/showthread.php?p=16314#post16314 I wasn't aware of the injector issue in E30s, but it sounds like it improves things. If you're just changing the chip, for these old cars, I can't see how one chip would be substantially different from the other. Dinan has a fabulous reputation though. FYI, Dinan says they still have a pile of chips for E30s (or at least the 318i). They are currently the least expensive option (compared to Bav Auto or Turner chips).
I think Dinan has a very good marketing department. I like Jim Conforti chips, personally, as they tend to make more power under the curve. You can get them from Turner. I have not tried the Mark D chips yet, but I might when I get the E30 back online.
Who distributes the Dinan chips? I always have ordered parts from Bavarian so I don't know who else sells parts for BMW's in generally except the dealer.
http://www.dinancars.com/ I am probably a bit bias toward Dinan since I have to pass a California Smog test every 2 years and Dinan is a California company, so I feel a bit safer with them regarding tuning for emissions compliance.