Doing head gaskets on 08 Impreza..There are two different sets of installation instructions. The instructions I'm used to are middle two head bolts to 25 ft/lbs, outer four head bolts to 15 ft/lbs ,along with a couple of additional angle torques..
The other set of instructions are all six head bolts to 31 ft/lbs, along with a couple of slightly different angle torques.
Which installation instruction set should be used for 08 Impreza ? Also I've seen YouTube videos where the 21 ft/lbs then 51 ft/lbs torque and then two 180 degree loosening steps are omitted. The rational is these steps are for head bolts stretching, and if you are reusing the head bolts ,they are already stretched. Which method is correct, re stretch the head bolts or not re stretch the head bolts ?