When first switching off ABS, you’re gonna lock up the brakes. Reducing braking pressure is not the answer. You need to do lots of laps and lots of braking for corners. Forget about tuning. Learn how much brake you can give before they lock up and learn it so well you don’t even have to think about it anymore. Choose a track with long straights into big braking zones, like Sebring and road America. Many of the corners here require that you brake straight and hard and will learn you what’s the most you can get away with. Of course not every corner requires this approach, but you need to know this first. As you develop as a driver with lots of practice you’ll get a feel. You’ll hear trail braking mentioned a lot. This is simply a case of staying on the brake a bit longer than would seem is necessary and it’s used to keep the weight of the car over the front tyres and give us a bit more front end. If you want to practice it I can’t think of a better place than the last corner of long beach, just stay on the brakes a bit longer to get that front end round. I use 150% pressure.
As for brake bias, it’s important! The lower the percentage, the more the car will rotate under braking. If the percentage is too high you won’t be able to get your car turned in for the corner and it’ll cost you a lot of time. If it’s too low it’ll rotate too quickly and be difficult to manage. Try 45