I have a pheonix gold ...dont remember the model number because I installed it about 7 years ago, but it puts out 175 amps on a Dodge Ram 50.
About the horse power statement. Technically yes, your engine needs to work harder, but you wont notice it. You cant even feel horse power to begin with and 2nd it will not affect your gas miliage. I have been using this alternator for 7 years and my gas miliage is the same.
I use a battery isolater to 2 red top optimas and never have had any issues running my 375 amp stereo (300 for bass and 75 for highs). Never cuts off and never goes below 12 volts.
I would look into a Stinger dealer. They usually will set you up with the kit and instructions. Its not cheap though.
Don't go dual alternator. There is nothing wrong with it, but you can get alternators even higher than 200 if you have the money.