maybe this helps...
1. patch your game to 1.02 (you have already done this...)
2. make a new folder: c:\newfolder
3. copy your cars.wad and your f1gstat.sav from your gp4-directory into this new folder
4. copy a decrypted exe version 1.00 (!!!!!!) into this folder. if you want, rename it to gp4_old.exe or something so you cant get confused with the two gp4.exes
5. you have now a folder c:\newfolder with 3 files in it. make sure they are not read-only
6. start gp4master. configure it to point to your gp4_old.exe in the new folder.
7. now you can use gp4masters wad-workshop and tex-workshop. this updates your graphics and will no doubt lead to further questions in this forum.
greetings and good luck, jp
ps: dont worry, we all spend a few nights editing gp4 from time to time, trying to find out how all this works togehter and losing wight...
pps: if you want to edit team data like driver performance, driver names and team performance (bhp), gp4master will not work !