I have never looked at this game but I think it has a checksum in which case unless you know how to fix the checksum you will not be able to mod it
Your using the test drive mod tool in 360revolution right? Make sure you save / rehash and resign the file after modding.
Good call I didn't think of that coz I'm still half asleep also didn't notice it was in the 360rev support section either lol
There is a known issue with the Title Update #3 and the save. It changes the save and slightly encrypts it. The only resolution is Make sure to delete your cache, load your save in the game -- you will loose ALL DLC content -- save it, then use the editor on your save. If that doesn't work then you will have to edit the save before applying the Title Updates/Mandatory DLC Updates to your system that will effect the save.
I have a better method, if you want to play online, clear all mandatory updates, and clear your cache, then make a new save, and when you get to your house, put the save on a usb, go to 360rev, mod it, go back to your xbox, download all of the mandatory updates, and then viola you can play online with your modded money.
this thread is 3 weeks old, and OP has not logged in for 2 weeks, im going to assume the solutions above has worked. Thread locked and moved.