I was wondering if you can run the greddy piggyback unti on our OBD II systems. I have a 2000 cavalier with the 2200 motor and im goin na. Im lookin to add a couple hp by tuning my a/f ratio and my spark timing. Just wondering if the greddy emanage unit would work on my car or do I have to use HP tuners?

eManage will work, however I'd say get the HP software. For the money you'll get better bang for the buck. The HP software requires no wiring (for basic, at least), where the eManage requires some wiring since it's a piggyback. Remember that the eManage can only work within the ECU's programmed parameters so you're only going to be able to get so far before you run into a wall. HP eliminates most of those limits as it actually allows you to alter the parameters themselves, rather than trying to work within them. Just make sure your PC is capable of supporting the HP software - requirements are in the FAQ - and do some reading on the software itself so you know what to expect.