This may sound counter-intuitive, but try narrower tires. I was able to fix the dreaded “high speed death weave” on my fast MR cars by doing this (oh god! it’s weaving under throttle at speed! i’ll just ease off the throttle… woops. now I’m pointed backwards, or spinning wildly towards certain doom). I’m not sure why this is going on, maybe a tramlining effect?
Any RR car will understeer at full throttle unless it has enough power to instantly blow the tires off or the rears are already sliding. So part of your problem may be understanding weight transfer and vehicle dynamics? And part of it may just be the car’s natural dynamics, I’m having a hard time adjusting my 3.5V8 RR not356, too…
Generally speaking, increasing roll stiffness (shocks, springs, antiroll bar) will decrease grip at that end.
This is probably a different animal, but I have a 1600cc boxer 6 in that (75 not911) body style. Handling preferences are personal, but I like the way this one drives. (I drive on a wheel, no idea how it will do with other input types). It’s completely analog (no ABS, TCS), I’ll post it here if you’d like to try it for comparison.
NG Rallysport - street v2.car (22.9 KB)
edit: woops. this one’s not analog, but I like it better with the tcs off.
NG Rallysport - street turbo.car (22.9 KB)
road car with turbo
NG Rallysport - test.car (22.5 KB)
edit: also has tcs, my bad. I like this one with tcs off, diff locked. This would make a car awful in RL, but not in BeamNG
edit to add: My method: Hard on the brakes before the corner, get your downshifting done in a straight line. Still off the throttle, or lightly trail braking, tip it in towards apex. Control rotation with throttle/brakes as necessary. If it’s oversteering, add throttle to shift the weight back to the rear. Once the car is mostly rotated (hopefully near apex if you’ve done it right), roll back into the throttle. No amount of throttle will unstick the rear at this point, but the front will go lighter the more throttle you add. When it’s pointed where you want it to go, let 'er eat.
Hope that helps.