Max stats SP

where can I find trainer to the max stats in sp?

Just use script hook and a trainer that uses asi mod - I think Simple Trainer v2.8 or Menyoo (SP) will have this options you after

Then when you want to be go online mode, remove all the files that not in the gta folder before.

I don't play it at PC, but I would try it with an Savegame.

Just use the savegame editor no shitting with files that nerd to be placed and removed etc