anyone use powermaster alternator?

Before you go blaming your alternator for the dimming headlights issue, fix the problem that is causing it. Compare the voltage at the headlight socket to the alternator output with the engine idling. I'd be willing to bet it's actually lower than the static battery voltage (engine off). I've seen cars that drop below 10 volts at the lamps, and never get much above 12 when the alternator is producing 14.

Your problem is resistance within your wiring harness causing the voltage drop. Start at the headlights (and taillights) and work backwards cleaning the terminals, especially the ground wires. A ground down metal fingernail file helps to clean the connector sockets, and 220 grit sandpaper works great on the blades, terminal rings, and body metal. When you get to the firewall connector, inspect it carefully to make sure it hasn't overheated and melted (common). This is especially important to do if you do install a higher output alternator down the road.

Also, your negative battery cable should have a body ground pigtail. I've seen a lot of replacement cables where this isn't hooked up. Other things to look for would be crappy clamp on type replacement battery cable ends, crimp-on terminals and general wiring hackery.

A bigger pump won't help if the plumbing is clogged. The factory alternator has enough power to set the wiring on fire, a high output alternator will just do it faster.