Need help from newbie

Hi everyone
I'm using the internet package from TWC (Spectrum now) and I have the modem Motorola SB5101 that has been modified/hacked and the speed can go up 15Mbps. I really want to learn how to make it faster so it would be great if someone can teach me step by step cause I don't know at all. I would be appreciated for your help. I'm leaving in OC CA so please help me. Do we have some solution can make speed about 100 mbps? please be advised

Thanks