Originally Posted by homwerk
Another thought is doing multiple PC-2000s too. Is that a good option? I think they are rated similar to my current Outlaw only I'd be happy getting 2-3 of them right away.
You seem to be all over the place on what you are thinking. First, PC4000's; then something even more powerful than PC4000's; and now something less powerful.
If I were you, I would take some time to try to figure out my goals. What is it exactly that you are looking for? The Ultra's will have more low-frequency extension and SPL than the PC2000's, and they are better quality subwoofers with more features and more user-adjustability. Ideally, you would start with two of the PC4000's, and just as with the PC2000's, you could always add additional multiples later if you wanted to. (You do know that SVS offers a free 45-day trial period on all of its subwoofers?)
Subwoofers which go lower in frequency, with more SPL, will have a different sound and feel than your current Outlaw sub, or even the PC2000's. That extra bass weight is more important to some people than it is to others, especially for action movies. When you asked about even more powerful subs than the PC4000's, I mentioned the Cap 2400's, with an even lower port tune. That is one way to think about ported subs.
The PC2000's are tuned lower, with more power than your Outlaw. The PC4000's are tuned lower, with more power than the PC2000's. And, the JTR subs are tuned lower, with more power than the PC4000's. In each case, "power" doesn't simply refer to amplifier power. It is a combination of driver size, motor strength, excursion, amplifier, cabinet volume, port tune, and DSP, which determines at what frequencies a subwoofer will be powerful.
As the lowest frequencies are harder to achieve, especially in larger rooms, subwoofers have to be more "powerful" to play those frequencies with real authority. And, we have to pay extra for that. Once you decide what you are really looking for, that your Outlaw doesn't give you now, you will be in a much better position to make a good choice. Personally, I think that your first instinct was correct. I believe that a pair of PC4000's would be an excellent solution for you. And, if not, send them back for a refund and get something even more powerful. I really wouldn't go down from the PC4000's, though, based on everything you have said.