how to downgrade jelly bean to ics for lenovo a516?

[wandragon]

alright so here i am going to tell you all detail about my problems. i am using lenovo a390 and my little sister is using lenovo a516 .. so the problem here i want to downgrade my little sister jelly bean to ics because lenovoa516 using jelly bean it has become lagging from what i can observe .. so im honestly need help from anyone who know how to downgrade jelly bean to ics .. i want to downgrade my little sister lenovo a516 to ics as i am using which is android version 4.0.4, buld number a390_row_s316_130730 .. pleaseeeee anyone who has experience downgrading and anyone who is expert in downgrading android version please tell me detail how can i downgrade the android version .. please tell me how to do it detail and where, which file must i download and of course please give me the working links to download the file and also clean of any virus ... i need anyone response ASAP ..