There are three things that affect braking for the most part. Rotor diameter, pad surface area and piston surface area. Although more pressure can be an upgrade, but brings higher temps on the rotors in a panic stop. Rotor diameters have been increasing, hence the 16 and 17" wheels to clear those larger rotors. Also as brake pad area increases, more rotor pistons are being used. But if you go to larger diameter tires, I don't think I would go to slotted rotors. Those are more for high speed applications. There is a fourth thing that has come up in the last few years. Different lining materials. The softer the material, the faster you stop, except when you get them too hot. They also wear out fast and leave a ton of dust on your wheels. If you go to the other extreme, and I did on one of my work trucks, then you can put tough as nails lining on that needs to get hot before they start working well. But with a 22000# GVW on a one ton Power Wagon that was real handy.

Now there are ceramic linings which I favor. Good on cold temps and never fade, and there is an improvement stopping power too. So I put them on all our cars and the Jeep is getting a set. If they are not as effective as I want, there are some solutions from Willwood for instance that are bolt on and will stop anything, but six piston calipers are not cheap