Hey Raul!
Nice to see you again. It's been a while since GP4. I used to paint under the name Hagi.
So, you only need to copy sa2_gen_low_main in the cars/lr2/livery_main folder, rename it to sa2_gen_high_main and paste it into the textures_high folder. The sa2_gen_low_main is 4096x4096px large.
SK Racing: Thanks. I might make good use of it for the next project
There is a little bug in the specocc around the front wing, where the red and white parts are. I forgot a layer in the file for the red channel. The update will be up tomorrow