amps and alternator size

i have 4500 watts worth of amps and 8 piaa lights at 70 watts ea ia a 160 amp alternator big enough to support all functions at one time?

The answer to your Questios Is "No" you would need Like a 300 Amp Alternator But They don't make one in Marine so you and I are in the same boat my friend. 165 is not enough but it's better than the stock 65 Amp.
http://svtsupercharged.com/gallery/alternator

Amps and speakers are generally rated at their "peak" power rating, which is often twice the "rms" or "real" power. Thus, the 4500 watts is more like 2250 watts, which would require 187 amps from a 12 volt source. Now, the thing is that it would only draw that if you had a constant tone and the volume cranked all the way up. Assuming that your idea of easy listening isn't a jet engine the average power to the amp will be far less.

The lights are an easier calculation. When talking about a light, a watt is a watt, so 70 watts at 12 volts is 5.3 amps. 8 of these would suck down 46 amps.

If you need the lights, you shouldn't be wakeboarding. If you aren't wakeboarding, then you shouldn't need 4500 watts of amp, unless your real objective is to annoy all the fishermen and cruisers. Just turn the volume down when driving at night and you should be fine with a 160 amp alternator.

If you are really worried about it, it would not be too hard to measure the current flowing into or out of the battery. Get set up to measure, get the engine turning 2000 RPM or more, turn on the lights, crank up the stereo and see if you are putting current in or taking current out of the battery. If you are operating at maximum load and you are putting at least some current into the battery you should be OK.

I did a Test On My Natique. I would start the boat and turn things on One at a Time to see how much juce thing's took. This is Before I Installed the New Alt. The tower lights don't draw or suck as much juce as the Running Lights. I know it sounds kinda Funny I don't know why.Im talking about the bow and stern lights they take lots?. The Heater Suck's the most Juce,

So This is a real life Situation. Your out partying Playing your stereo. You run it for some time till it get's dark and time to go home And Your batterys are now Low!. Then you fire up the heater because it's chilly then you turn on the light's because it's dark, Yes this happens I found my self running like below 11 volts. I know this can't be good, That's why I upgraded sooner or later I knew the thing was gonna give out.

Grant there is no way your bow light and stern light are drawing more then tower lights unless your using 12 watt and 5 watt tower lights because thats what most are rated at. One tower light is like 50 watts minimum. Now the heater is definitely a sucker.
Rod almost all quality stereo equipment is rated at RMS levels not peak (sometimes both but never just peak unless your talking kraco or wal-mart crap)