A fair bit of the info has come out in this thread but there is more. The options really are thus:
1. Standard SC brakes in top condition with race pads, race fluid and cold air ducting. It can be made to work. I raced and prepared a 2.4E with essentially these brakes and used Pagid Orange pads and Motul fluid. Pads lasted about 2 days and the car only weighed circa 1000kg, put it sure stopped.
2. Carrera fronts and SC rears. A bolt on and relatively cheap to boot. Gives you the benefit of a 24mm thick disc and a wider throat caliper. With ducting this may be enough for a heavier occasional track day car on R-tyres. The right pads will give you enough clamp force to lock your tyres wet or dry. As an intermediate step up you could substitute Boxster calipers rather than 3.2 - but you don't gain much with just a caliper change.
3. 964/944T/Boxster calipers over a 944T 28mm thick disc and Carrera rears. A good step up in front disc size gives you a decent increase in thermal reserves. I recently did 2 track days in hot weather with no ducting and had no issues in my heavy G50 Carrera. you also get a lighter, stiffer caliper that is nearly twice the size and has much bigger pads for longer life. This set-up should be ample for even a 300+hp track car as it is basically what the much heavier 964 has. Works fine with a std small master cylinder but Carreras need to remove the proportioning valve for proper bias. SC rears would be overly front biased with this set-up as it is slightly front biased anyway with 3.2 rears. The front disc needs a 5mm bearing spacer to clear the strut so you gain 5mm of track or lose 5mm of clearance for your tyres depending on how you look at it. I don't think this set-up fits in a 16x6 Fuchs wheel so 16x7 fronts are required.
4. 930 turbo front and rear. A big step up in thermal reserves as you go to a 12.75 inch disc that is 32mm thick in front and a 28mm thick rear disc. Calipers are old tech with non-differential pistons etc, still its the gold standard if you want to run Fuchs. Fits in 15s or 16s - as 16s have very little more room for brakes as the centres are virtually identical to 15s. You can run 993 front calipers and 965 rears for a more modern set-up but, IMHO, the fronts won't fit in a 16x7 Fuchs without modification/spacers unless its a 951 16x7/8 that has extra caliper space. Discs are expensive as you have to go for a custom zero offset mounting bell for the front and then choose a disc. I would never buy discs from the breakers ! 930 brakes need a turbo master cylinder and I think you need to do all 4 corners as even Carrera rears will be too small to give close to the right bias. I recently rode in a car with this set-up - 930 front and 3.2 rear - and while the owner tried different pads to correct the bias, it was nowhere near ideal. It meant braking from nearly twice the distance I was braking at - so yes it does make a significant difference.
5. Big Red or GT3 or GT3Mk2. The sky is the limit if you have big enough wheels and a big enough wallet. Big Reds are not much bigger than 930 - 322mm x 32mm - but the calipers are a great design (discontinued as the moulds have worn out) for street and track. 350mm or even 370mm discs are possible if you need to do endurance races !
Before deciding where you fit on this spectrum you might ask how fast your car will be. I know race cars with 600hp running turbo brakes so do you need this much brake? After all its a lot of extra weight to carry around. Just pick up some 930 discs some time, they are massive. If you are going to build a track car, then you will probably build it light in which case you need less brakes. Just something to consider. Andy's CS and my 3.2 brake pretty much as well as anything up to GT3RS with just mild upgrades at a fairly reasonable cost. Threads on my brakes and Andy's are in the 3.2 forum. Pic attached of 964 caliper over 28mm x 298mm 944T disc.
HTH
Richard
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