Fitting 306 rotors and calipers to 205 Si.
As mentioned by others 306 rotors and calipers are a direct fit onto a 205 Si.
The rotors are the same diameter, 247mm.
However the 306 rotors are ventilated and thicker.
306 calipers are bigger than Si and have greater pad area.
Fitting is quick and easy with the hardest part being getting the rotor retaining screws out.
Took about 4 hour but in that time I also changed LH driveshaft and LH strut and drained and refilled auto trans.
The brake changeover itself would take less than an hour plus brake bleeding time.

Si front brakes

306 front brakes fitted to 205 Si.


rotors

Calipers

Pads, Si top 306 bottom.

Pepperpot vs std 205 Si wheel.
Only disadvantage is that the standard 13” wheels will no longer fit.
They foul on the larger calipers.
14” pepperpots fit nicely, but change the overall gearing.
Si auto used to sit on 3k at 100 kph with standard wheels/tyres, yet to check present setup with Satnav.
By contrast my GTi series 1 which (originally fitted with pepperpots as standard now shod with 15” speedlines from a series 3), sits on 3.25K at 100 kph.(Satnav).
And of course you have to carry a pepperpot spare unless you are prepared to carry two jacks and a set of std wheel bolts.
So far I’m impressed with the greater stopping power.
Waiting for brakes and tyres to settle in before trying them out on the Gillies Range road.
I was getting brake fade on the downhill run there if I got enthusiastic.
Could have been poor pads or other problems though.
The pepperpots and larger section tyres reduce body roll and enhance the handling.
Si wheel/tyre, 12.3 kg, 175 cm circumference. (165-70-13”)
Pepperpot, 14.5 kg, 181 cm circumference ( 185-60-14”)
Si rotors 3.09 kg, calipers 2.6 kg.
Didn’t get around to weighing 306 rotors and calipers but they are substantially heavier.
Now to get the rear beam sorted.
Paul