downgrade ps3 slim 4.11 to 3.55 cfw

is it possible to downgrade you're ps3 4.11 slim to 3.55 cfw??

please help me:)

Yes, it is mostly possible, it depends on what model you have... it needs to have been delivered with a system version of 3.55 or lower, and it can't be one of the newer 3k models, check google for E3 flasher compatibilty and you'll see ;)