possible dangers of ho alternators?

I recently at my local Ford dealership looking for a high output alternator for my 2001 grand marquis. I assumed that they had one for some sort of police package. They did although they told my that the mounting brackets are different. The parts guy seemed pretty intelligent and he warned me that if I were to find and install a high output alternator in my vehicle that it could create power spikes that the vehicles electrical system wasn't designed for possibly causing say the computer or several other sensitive components to "fry out". I would like to hear from people who have experience with ho alternators and if there are any risks to using them in a stock  01 grand marquis. Do they create voltage spikes that are dangerous and if they do, couldn't the power be smoothed out with some sort of capacitor set up?? HELP!  There are so many people out there that are willing to feed me bs without really knowing what they are talking about.

They will create "voltage spikes" if the "voltage regulator".....(key word here) is shot, not there, etc. The parts guy has knowledge of the part, and the brackets.....but he is miss informed on the rest.

H.O. alt. with a functioning voltage regulator, good battery....consider "the big 3" And your rollin.