9-3 '06 1.9 Tid Sportwagon rear brakes

[Petemate]

Tomorrow I'll be replacing the rear discs & pads. I have the promised loan of a piston wind-back tool, but have not seen it yet and need to know if both pistons wind back clockwise (Haynes says clockwise but someone told me that some cars have opposing directions) Also a bit concerned regarding the caliper carrier bolts (God knows why they have to be so tight - on other cars I owned with similar sized ones the torque was nowhere near and nice and easy with nice 17mm-headed bolts) I have read somewhere that the carrier Torx bolts on the fronts are E20 and the rears E18. But I have been under the back and cannot seem to wriggle my E18 on (maybe a bit of crud on the one I tried, & an E18 needs a gentle 'tap' to seat it?) The sockets I have are 3/8" sq drive and I know that there is no way I will be able to undo them with 3/8" drive gear, so will be buying a 1/2" drive socket tomorrow (and I DO have a nice meaty breaker bar) but really would like to know if someone can confirm what size they are?
This post has also gone on the UK Saab forum but that one is nowhere nearly as active & quick as this one!
TIA
Pete

[Petemate]

Well, got a few quick responses from the UKSaab boys after all. If it helps anyone on here, the job was mainly an easy one - wind-back tool was needed; the carriers had to come off to get the discs off; the Torx socket size is E18; the pistons both wind back clockwise and the top carrier bolts are bhES to get at as the upper suspension bolt theads stick through in the way, but not impossible.
The genuine discs & pads were very reasonably-priced from the Saab dealer, coming out at the same price as Elk parts but naturally without carriage charge (we are only 4 miles from the dealership)
Chuffed with the result, only about 3 hrs work and one skinned knuckle....