I know people who have spent money on driver training and are then consistently faster in anything they drive than people who upgrade.
Getting good safe tyres is a must for predictability, but nothing beats knowing what you're doing out there - as instructed by a professional, not just believing your own hype. Unless you're lapping within 0.3-0.5s per lap at wakefield then you don't need more power / brakes, you need to learn to use what you've got.
Changing pads makes more difference. EBC yellow / green stuff pads are old news; these days Ferodo DS2500 / DS3000 are the good gear and will pull you up like you're hitting a wall, but still give you pedal feel.
There's no point in boosting your brakes if your pads are crap.
Speak to a brake expert like Competition Friction
Brake Pads - Ferodo Racing and see what they recommend for your calipers.