I was looking into Black Ops zombie mods and seen that they use modded gpd's. I dont play online because my connection is unreliable. I wanted to find out information on using modded gpd's. Is it only jtag or can retail work? Can a guy get banned using a modded gpd offline? Can they corrupt the xbox in any way? Thanks in advance for any info anyone can provide or even a direction they can point me to for answers.