Alternators and proper installation/operation of alternators is one of the most mis-understood aspect of proper wiring.
1st, You need to calculate proper pulley size. A general rule of thumb is, 140mm alternators are rated to approx 14,000 continuous rpms, 130mm are rated to approx 15,000 continuous rpms and 120mm alternators are rated to approx 16,000. Calculate out your alternator rpms by multiplying your max engine rpms (rev-limiter setting) by your crank to alternator pulley ratio. Change your pulley sizes until you are close to the numbers above. Operating your alternator at the maximum rated rpms will not only increase the output efficiency of your alternator, it will aid in cooling potential of the alternator internal/external cooling fans.
2nd, Insure you are using the appropriate wire gauge from the B+ on the alternator to your battery. Google "Wire gauge calculator" and you will come up with several on-line wire gauge calculators for determining appropriate gauge. You want to shoot for no more than a 1/2 volt drop from your alternator to your battery at max alternator output.
3rd, In my opinion, avoid the one wire alternators. Alternators have a sense lead for a reason, to sense the necessary output to insure your instrument panel has 14.0 to 14.2volts at all times. This sense lead will aid in overcoming excessive voltage drop as components are cycled on and off, and aid in eliminating over charging which can cause premature battery failure. While these 1-wire units may be easier to install, they are not operating in the most effective manner.
4th, Insure you are not experiencing belt slippage. If you are running a V-belt, anything in excess of 140 amps output should utilize a 7/16-1/2 inch wide belt over the more common 3/8 inch wide belt. Not only is the wider belt stronger, it has greater contact surface area aiding in preventing slippage.
5th, Your problem may not even be related to your alternator. Unless you have a proper current clamp, you have no knowledge of the actual amperage your alternator is putting out. So, to say your alternator is not putting out enough "AMPS", may be an inaccurate assumption.
You must insure all wire sizes in your vehicle are appropriately sized for their respective current load. So, calculate and/or properly measure actual current draw. Then use the above on-line calculator and insure the wire size to your instrument panel and on to your actual components are of adequate size. Or, use a volt meter attaching the negative lead to the +12V wire at the component, and the positive lead to the positive post of your battery. The reading on the volt meter will tell you voltage loss for any given component you measure. Automotive industry standards are to have no less than 1 Vdc loss to any component. If you have in excess of 1 1/2 to 2 Vdc loss, your problem may be outside of your charging system. You need to perform the volt meter test with all components operating simultaneous representing worst case continuous draw.
If you have additional questions, feel free to send me a pm.