It's two torx screws, a quick fuel disconnect, and a 8mm nut on the fuel line to the rails....
The only thing I can think of is if the the new spring is really strong making it difficult to install..
Technically you are supposed to align the the engine to TDC so the cam lobe the HPFP rides on is at its lowest point... this makes it easier to put the the HPFP in as you don't need to compress the spring much to get it in....