Ok, a while back i installed a 100+ amp from an olds firenza (recommended on this site) and i just now noticed my problem (i've had it since i installed it though). When i'm driving at night with my headlights on, (from a stop), i accelerate to about 2,000 rpm's and the headlights and all electrical lights (stereo, dome, dash etc...) draastically dim. To the point where it is hard to see the road. If i have the high-beams on, the stereo lights practically dissappear and the high beams are so dim, they look like running lights. Also, i rewired the car (1971 chevelle btw) with a painless wiring kit. Before i bough the alternator, i had a lower amperage one on there and had no problem. Also, the wiring kit has no voltage regulator for the alternator. Thanks for your time!

Are you sure the belt is not slipping. When the lights are dimming the battery's not charging. Do you have "dimming problems when the lights are not on? Since the car has been rewired, I would need a better explanation of the wiring. It would also be best to add a voltmeter in the car so you can monitor the charging system.

If I understand you, the lights get dim with increased engine speed?

Or put another way they are brighter at idle? That sounds like a regulator problem in the alternator. At idle with significant load the alternator is probably running full output with no regulation. As RPMs increase so does the alternators output, so the regulator kicks in to limit alternator output and voltage.

The voltmeter would be a good idea so you can characterize it better with real voltage numbers.

you wire it right? http://www.chevelles.com/techref/ftecref14.html