Why do I have a Bose amp?

Guard Dad

As some of you know I've been trying to do some low budget upgrades (Polk front speakers and tweeters) to the 2010 base audio (non touring) system. So far so good. My question is why do I have a Bose amp on the floor just behind the seats? I've seen pics of the 2009 and didn't see an amp, is an amp normal in 2010? This has me wondering if I can somehow use the amp as the basis for additional upgrades.

For the most part, I've been frustrated in working with the stock unit, it won't take an integrated ipod and desperately needs more base. Even though I don't really have a budget for it I'm checking out new double din head units ($200-350) and an under seat sub ($225). I want to keep it looking stock-like and don't want a sub box because I need the luggage space for weekend trips. Want ipod interface and steering wheel controls retained. Should I consider HD Radio a must ,or is it no big deal?

So should I just kiss off the the stock stuff and move on. Looking for some real input here.