Fitted the dogbone mount today along with the yellow powerflex insert.
Dogbone Old Part Number: 1K0199855AE
Dogbone New Part Number: 1K0199855BJ
Powerflex Insert: PFF85-504
The big bolt that goes through the bushing was really tight, and it didn't help that it flexed due to the bushing, but managed to get it off with the help of some WD40 and a 600mm breaker bar.
Car seems to drive a little better -- a bit more thrusty when accelerating. I think it will get better again when I replace the left and right engine mounts (still waiting on the parts).
I was a bit apprehensive about fitting the powerflex insert in to the subframe bushing as I heard it can cause the car to vibrate uncomfortably when idling. But it's absolutely fine. No negative change at all. I think this might just be a problem on Mk7 Golf GTIs with a bushing that is still in good condition, as the reports of an increase in NVH seem to be related to fitting this bushing to newer GTIs.
A lot of the tutorial videos use a trolley jack to force the insert in, but for me it slid in really easily by hand (with the help of some silicone grease). I think this just goes to show how worn the bush is on my car, so the insert is probably just taking the car back to its old strength rather than making it stiffer than stock.
Anyway, in case anyone plans on doing this, these are the torque specs from the manual (
bpy_10-engine-removing-and-installing.pdf):
Two smaller bolts toward the front of the car: 40NM + 90 degrees
Big bolt going through the subframe bushing: 100NM + 90 degrees
Thanks again for all the help.