<h2 class="title icon"> </h2> Ok then, This is my first attempt so if it goes wrong plz dont get on at me. I've decided to go the gt4 route mainly because of cost but to be honest when i done it after the the st182 twin pots i decided to buy all new because it was stayin on, As you all know standard brakes are rubbish, Twin pots abit better, This set up much, Much better. Firstly get some astra cdti discs, There are 2 types one with a 70mm hole but get the one with the 60mm hole its almost a perfect fit. Take the discs to a machine shop and get them to take 1.5mm off the inside where it mates to the hub and 2.5mm off the outside diameter so it ends up 278mm before machining after machining Stick your caliper on, Quick bleed and away you go...Happy days Heres the difference in the caliper carriers as well See how bigger the gt4 on the right is, I'd just like to say depending on which wheel you are using, I had to shave a little off the front of the caliper carrier and fit a 3mm spacer in £10 off e-bay for 4. The wheels i am getting there is no need for the spacer. discs........£66 calipers....£100 machine...£20........£186...Best money i've spent on the car Second hand discs and calipers you'll be grinning all day