Are you hitting then on entry before the apex, or after you commit to the throttle?
The second is harder to deal with - you have to wait a bit.
If it's the first... try leaving the car in gear and not changing down in the early part of braking. You hear racecars changing down, sure, but every time you change gear you're upsetting the brake balance of the car and grip on the driven wheels. In heavier roadcars on lower grip tyres, this is a bit of a problem. Try holding the higher gear and then banging down the ratios just before the apex when you've scrubbed off all the speed. You should find the car is better behaved on the entry requiring less control inputs to upset your line before coming off the brake.
The first can also be dealt with in tuning somewhat - for RWD cars at least. There are four ways to adjust your car's turn-in in tuning, apologies if you're heard this all before:
1: Spring rates
2: ARB rates
3: Brake balance
4: LSD Decel value
The problem with the first two of these is that they affect the whole car. The latter pair are easier to deal with.
First question:
1. Does the car seem to oversteer (tend to go inside of the racing line) or spin/become tailhappy under braking?
If yes, then you (may) need to reduce your rear brake bias. But you need to consider the second question:
2. Does the car simply become unstable off-throttle, or remain unstable after braking is removed?
If the answer to this is yes, you need to dial on more
LSD Decel. For 450PP cars at roughly a tonne, you shouldn't need much LSD for
acceleration. Values might typically range from 5 to 15 for both Initial and Accel. Certainly the stock 10/40/20 is far too aggressive. Let's say you're set at 10/10/20. Increase the decel by 10 at a time (in this case, to 10/10/30) and retry. You should find that the car is not turning in as aggressively as before when you hit the brakes.
The physics of this are relatively simple, if not obvious. Without an LSD, as you brake, while brake force is being applied at the brake bias you set, each rear tyre is braking independently. As you turn, the lightly loaded inner is more liable to lock, plus the outer rear (which is doing more work) is liable to lose grip
laterally - and as soon as grip's gone, the tyre is more liable to lock. ABS helps, but it's a crutch.
With an LSD, as you come off the throttle, the LSD Decel value comes into play, and the LSD tries to tie both wheels to the same rotational speed. Not just speed is affected - the point is to also share torque/load/grip between the rear tyres. Effectively the outer rear tyre is gaining traction as it is sharing some of its load to the inner... this causes the car to rotate less - reducing oversteer. This effect is more pronounced as you brake, as the brake torque is also more even as the grip is more even between the wheels. The chances of one wheel locking are reduced - as the speed reduces due to the loss-of-grip-lockup, the LSD tries to share it out to the other tyre. If you do lock-up it's going to be both. This will snap the car out into a spin in a hurry and is a surefire way to let you know you have too much rear brake bias.
Increasing the LSD decel to 60 will illustrate this in gross terms. The car should now hardly turn-in at all compared to what you expect. You might find you stop very well, just not on the line you want. Finding a balance of LSD Decel and rear brake value is now your goal.
Oh. While we're talking LSDs, in the Golf I set it to 60/60/5. I'll take ALL THE TRACTION, please. I don't care where the tail's going under brakes, it's all front end for me.
). I'm a casual but I drive with a wheel (DFGT). My only concern is tuning - I suffer from tuningofobia but I'd like to participate anyway 
