(adsbygoogle = window.adsbygoogle || []).push({}); just got a new ps3 but it is on fw 3.66

nope, only by soldering or an E3 flasher

You need to install a E3 Flasher or a progskeet to downgrade. But I think that the ps3 had to have been on 3.55 or lower at one point to actually be able to downgrade to it.