Hello, I have my Corsair H60 cooling my i5 3570k @4.4GHz and am wondering if putting two Corsair SP120 Quiet series fans in a push pull configuration would perform better than my single stock Corsair fan pull air out. Would it be quieter? Would I see a significant drop in temps?
Depends on how you define "significant". I myself have the Kuhler 620 (similar to your H60 performance wise and visually) and I lowered my temperatures by 5-7 degrees with push pull at load. Now is your fan exhausting air out? If so you will notice a difference when you change it to intake position, cooler air blown through the radiator fins yields better temperatures most of the times. Though obviously doing that would mean you need somewhere to exhaust that air (and for me it is the power supply, top mount).
Now to answer your second question. No it would not be quiet since the dba of the fans add up. Though don't think if you have two 25 dba fans then you obviously wont hear 50 dba of noise from those fans but rather something like 26-30 dba. So it would slightly be louder but not by much.