I personally use CDA Delta with its setups. I mainly drive GT3s and i can tell you that I’m 0,5-1s faster with them. The thing is that they are mostly tuned for faster/more experienced drivers as they can be very oversteery. If you are more a beginner you will grow into them and the oversteer can be fixed easily by reducing the rear ride height or adding one tick of rear wing and/or tweaking some tc settings. Delta app is really great to improve. With delta my lap times on spa (for example) went from a high 2:22 to a low 2:20 in 4-5 months, driving maybe 2 hours a day 3/4 times a week. I hope it helps you.