I was thinking about throwing a 2000 watt amp for my SA-10's, they are rated at 600 RMS, I am currently running a 1200. Will this make a difference an over all noticeable difference?
Im not familiar enough with SA's to say they would handle 1kw each, but unless they are ridiculously underrated (borderline stupidly underrated), Id expect thermal problems. At the very least you can expect it to affect the life expectancy of your subs. And at some point power compression is going to catch up with you also.
Usually when someone is wanting significant improvements in output, and they are already at the rated power of their subs, I recommending looking at other options to increase output potential. Such as the enclosure design, location, etc.
i agree with above post, your subs may be reaching thermal limits and power compression may limit output. and if your electrical system isn't up to par, voltage drop will further limit output from your amp. ideally, without any of these factors, you are looking at a maximum of just under 3db increase in output. in reality, i'd suspect that number is going to be much less.