are you using a good quality rattle gun with single hex sockets?

are you undoing the nut or the bolt?
i find it easier to undo the nut

the very first time i undo the rear was extremely hard and had to use the hydraulic jack to help force pressure to undo it

the fronts was/is easy

nothing sound stupid when you need help
sometime something so simple could make a huge different

for the rear (the suspension need to be push down)

What i did was put the standard jack between the chassis and the arm
than use a spanner or breaker bar (on the bolt) and hydraulic jack (on the spanner or breaker bar) to undo the bolt

be sure you point it the right way or it would make it very hard to undo or snap the bolt

I had real trouble with my left rear shock when I was swapping mine out. I ended up taking it to a mechanic and getting him to do it for about $50.

He basically took the car off and took at it with a 2m breaker bar. For a while I thought the breaker bar would go before the nut did.

Apparently Subaru has a habit of torquing up suspension components hard.

Strangely enough all the other shock bolts came off without too much trouble, although the opposite rear was still quite stiff.

spray with WD40 each night, then undo on the weekend. use breaker bar + torque multiplier or breaker bar + steel pipe (trolley jack handle). in desparate measures, use a good quality nut splitter, then replace the ~$20 bolt&nut from subie dealer. tightening torque at 160 N-m. good luck

3/4 drive rattle gun, your not alone on this one, I changed my struts on the weekend, the fronts were fine but the bottom bolts on the rear gave me all sorts of greef, finally borrowed my old mans 3/4 rattle gun and undid them