xbox360 need help with garage mod

[hotshot991]

hey guys!ok I don't know whats going wrong I simply want to replace one of my cars in my garage using hex editor with a gumpert or most likely a Ferrari 458 italia.But I have watched a dozen videos have followed each one step by step very carefully! but for some reason it never works!I have tried again and again and don't know whats wrong but I was wondering if one of you guys wouldn't mind me sending you my data or game save??? which ever you need and wouldn't mind replacing one of my cars with the 458 italia or gumpert or both would be fine:)lol but I can go over with you guys what I am doing but I have watched so many videos on it I really doubt im messing up somewhere

 

p.s.out of the like 7 times ive tried iv only have 1 freeze on my but all the other times ive gone all the way to garage and just nothing has happened but thanks and please respond back-jake

[Andreas¹]

What are you saying you have been doing? Modding on the Xbox isn't even possible as far as I know...