Lol at the wall... Joe I rocked some P2's way back in the day before they were even cool (probably 5yrs ago) in the rockford box they came in, and I have to admit they were ****in amazing subs. My dust caps are all but obliterated (still have them) but they still pound like no tomorrow. The thing about subs is this, it's not just the power going to them, it's the enclosure you use. Those P2's were on about 700rms because they are 250rms a piece, and they hit hard and loud. I miss them. Lol. If they fit in my mustang I no doubt would put them in. I'm currently using some sub by a company called 5 star audio on my rockford T400-2 and it's just not doing it for me honestly. It's in a tiny little walmart sub box because it fits in my spare tire well, but it's just not loud at all. Then again when I saw my ex's parents a few days ago I burned massive rubber and sent the car hella sideways quite violently and ended up busting the terminal on the box... Lol... At any rate..
Point is the enclosure makes all the difference in the world. General rule of thumb (and I'm sure Scott can probably agree with this) the larger the enclosure, the less watts you need. Meaning in a Mustang where space is extremely limited, you'll want a higher powered sub and a higher powered amp because your enclosure isn't going to be very big. My 15's had a massive box that took up the entire back end of my moms explorer and on the 3krms I threw at them those mothas damn near jarred my brain to mush. Then I bought a smaller box to save on some space and on the same wattage they just don't hit like they used to. So that's always something to keep in mind when making your decisions. Either way, I can highly recommend staying with Rockford for entry-mid range subs. And their amps IMO can't be beat. I love both of mine. Hope that helps a little