I am gathering all of my sub components for my '97 Ford Mustang. My question is whether to buy a stiffening Cap or a BatCap (http://www.batcap.net/Indexnew5.htm) to power the amp?
Umm... I'd upgrade my alternator before I'd spend money on a cap.
And with regards to batcaps, I don't have any personal experience with the things, but I have heard that although they can sometimes be a simple solution they really don't have enough reserve capacity/cca to make a good battery and too high of an internal resistance(ESR) to serve well as a cap.
Not positive this is actually the case(hearsay) and I'm sure there are some batcap owners here that will disagree.