how much easier can it get...
1) open bruteforce
2) decrypt your save data
3) open the gt5.0 file
4) press ctrl+F
5) type in your psn name
6) look a couple lines above
7) you will see a line of "F" (supposed to be 16)

change the first "FF" to 74
9) save and encrypt your data
10) go into garage editor 1.5
11) load your current car
12) click on the 'remove wing' checkbox(you need to have the highest wing installed like wing 3 if the car has 3 wings
13) click on "hybrid car"
14) copy save data to your ps3 and start the game and go straight into gt auto and do an oil change.
I cannot make it any easier than that so if you still getting problems you shouldn't be trying to mod anything