Picked up a 8200 and came with a alpine power pack ktp-445u. My question is it worth installing this power pack.. 45w rms x 4 when if I'm correct the factory head unit is 50w rms?

Yes, it is absolutely worth it, but requires running a separate power wire. The 8200 does 22 watts RMS (continuous) per channel and 50 watts peak per channel, so an increase to 45 RMS is significant. Just remember that you can't wire that power pack to the standard wire harness for the radio. At full blast, it will pull all the way up to the 15 amps that its fused for, in combination with maybe around 5 amps that your radio will be pulling. Factory wiring in pretty much every vehicle is only rated to handle 10-15 amps total. You could technically get away with it, but risk blowing a fuse and/or an electrical fire if you run it hard for any significant amount of time.