Best way to maintain SR, get a lag switch. Driving around with a 1 bar red connection makes you invincible. People don't dare to get close, and if they do your lag will push them out of the way with no consequences for you.
But more serious, don't leave the door open for dive bombs and inside overtakes, you can't trust anyone holding their line and leaving room for you when they attempt to overtake on the inside. 90% of my SR Downs come from people attempting to overtake on the inside, cutting the corner if possible and hitting me. So I now brake in a diagonal line straight to the apex when I don't trust the driver behind me. It's apparently too tempting to brake a little too late and use the other car to corner.
I had a funny incident yesterday. Car behind me was trying to get on my inside on the way to the sharp right before the bus stop chicane at Dragon trail. I didn't let him and we both ended up on the very right edge of the track. I already missed my braking point as I couldn't see it with him creeping in right next to me, yet he still insisted on out braking me. I barely made the corner, he flew into the wall. I swear most people don't start braking until after you do, just to overtake no matter what happens.