As a follow-on from my earlier posts regarding upgrading my brakes on Sierra uprights and rear sierra drum to disc conversion... I just got confirmation from RD that the discs that come with the Wilwood Front brake kit http://www.rallydesign.co.uk/product_info.php?products_id=10508 weigh an astonishing 4.7kg, thats not even a 0.5 kg saving on the stock Sierra vented discs.

Does anyone know of any alternatives that would offer a greater weight saving without having to sell a kidney?

I cant help with the brake disc weight issue but I would like to state that the Mintex 1144 pads a mega cheap on that page from RD.

I have been paying twice that for Mintex 1144. Im going to buy them from there from now on!!

No need for vented discs, you are stopping a car 1/3 the weight so a large saving here in unsprung.

Yiu can get the rears skimmed to minimum thickness.

I'm not going for vented discs, the ones in the kit are solids but represent less than 500g saving over the standard Sierra vented discs that i am planning to replace.

Problem is the solids are thicker than the single side of a vented if that makes sense. Only way your going to get much lighter is by going to 2 piece discs with alloy bells but won't be cheap.

Any recommendations as to where to try for 2 piece bells and rotors?

Have a look at 205 rear discs.

Not hi spec!

Have a chat with rallydesign as they do various 2 piece discs and are always helpful. You'll have to see if the weight loss vs cost is worth it though as they aren't especially cheap.

http://www.premiermotorsportdevelopments.co.uk/sierra-solid-ultralight-brake-discs---35kg-saving-195-p.asp

Some lightweight discs on that site

0.5kg might not sound much but it's something like 7-8% reduction and as it's both un-suspended and rotating weight that's a worthwhile saving. That said I might try a set of the ones linked to above next time I change pads.