[Q] bootloader allowed no and rom ¿¿?? topic

hello i have a question i have an xperia z rooted and when i was going to intall a boot loader i coudent cause i have boot loader allowed no so there is any chance to install like 4.4.4 pac man or lilipop and if not what can it do whit my decive rooted and whiout bootleader like what advantege i have that is rooted thank you :)