I posted this over in BC so let me copy/paste it here as well.
To remove mod-chip detection for Super Mario Galaxy, follow these steps:
1) Follow the first 9 steps in this tutorial:
http://gbatemp.net/index.php?showtopic=76657&st=0
*note: you won't need to download the Keysearch or DesWaD programs for this
2) Double click PARTITION (RMGE01)
3) Double-click SYSFILES
4) Right click main.dol and choose to "extract to file". Save it anywhere.
5) Locate your saved main.dol file and open in UltraEdit
6) Press Ctrl+G
7) Type in 0x4C0CCB and press enter. It will take you to the correct line
8) Change the 0C on that line to 04
9) Save your file and exit UltraEdit
10) Go back to Trucha Signer and right click again on main.dol. This time choose replace.
11) Find your new main.dol file and double-click it. A pop up window should appear saying file successfully saved. If you get an error, just close Trucha Signer and reopen it and reopen your iso file and try again.
12) Right click on PARTITION (RMGE01) and choose Trucha Sign It!
13) That's it! You should now have an updated iso file that will not give you the Error 001!