Yeah, I'm working up a procedure to grow the System Reserve partition on MBR initialized disks from what Win7 and Win8.1 create when they are installed 100 MB (steal 350 MB from C:, move C: to the right, then add the 350 MB to SysReserve = 450 MB).
It's fairly easy to do, not so easy to document
I had issues and a few other members got past install issues by doing this.
My 450 MB System Reserve only has 28% free space now - the contents are definitely larger than 100 MB
The size returned by dir /a /s doesn't match the above usage. There's a Recovery and the the System Volume Information folders that don't seem to be included in the dir count though
Total Files Listed:
93 File(s) 19,064,138 bytes
137 Dir(s) 133,562,368 bytes free
GPT initialized disks are not affected, one member reported that a new 450 MB System Reserve was created to the right of their C: drive. I suppose MS determined it was too difficult to affect MBR disks at install time due to the 4 partition limitation - most OEMs use all four (System Reserve, Windows, Recovery, Utility???).
The Technet MBR disk schema recommends 350 MB for a combined System Reserved / Recovery partition, so I just used that as a base and added 100 MB for good measure.