I have these on mine.
.
.
.
.
They are GT4 calipers and 315mm discs.
A bit of feedback for you.
The bias is completely wrong as I have not uprated the rears, there is much more brake fluid to now displace in the front caliper so there isnt as much braking force going to the front as there is to the rears, ive done 9 or 10 trackdays with these brakes on 1 set of pads, I use a set of rears every 2 days.
if I put bigger discs on the rear without altering the bias it will be even worse in terms of balance.
I will need a bigger master cylinder ideally as there is so much more fluid to displace
(which will be the same as all big 4-pots) the pedal travle is more than I would like, making heel and toe changes more difficult
(not impossible of course but harder), something to factor in on a track only car.
They never ever fade.
Ever.
The suspension is quite stiff, theres not alot of weight over the front wheels when compared to an front engined car so you are always fighting a losiong battle in terms of front end gip under braking.
They are powerful enough to lock the front wheels, which is all you need in terms of power, but, they are doing that using a much lower
% of there capability, hence they never fade.
You really need some very sticky tyres to push brakes of this size on a car like the MR2.
On the same not like some of the other lads have said the standard brakes with very good pads are a very good start.
The main area I lose time on trackdays compared to other fast cars is on the brakes tbh, not much, but im sure im trying much harder than they are!
A trackday with Jonb recently proved that bigger discs etc weren't helping in terms of braking, Jon braking in a pretty similar way to me
(with standard brakes but uprated pads), although my set up would come into its own with very sticky tyres
(assuming I sort out the balance issues).
Don't underestimate the Challenge cars! Bear in mind that power is not going to be a factor in your breaking, it's speed and weight that are going to be the key.
A one ton car with 500bhp is going to require the same stopping power as a one ton car with 200bhp at the same speed.
.
.
True, but with 500bhp
(and all other things being equal) you'll be arriving at the corner 20mph quicker!
though, but im not fussed about looks tbh, its the perfromance of them im interetsed in 
