In my BH I have a front strutbrace (STI), rear sway bar (whiteline), underbody k-frame (cusco), rear strutbrace (Z/S). They were installed in that order (months between each one).
Not sure how they will effect a BG/BP, but below is what I encountered on my BH
After the front brace, noticed no (maybe a little bit) difference. When the rear sway bar was installed I noticed a huge difference. The rear was less boat-like, centred/re-balanced a lot faster and has invoked less understeer and some more tail movement. k-frame really helped with the turn in and corner stability, also reduced understeer. The rear strut tower was noticeable, firm up the rear part of the car, felt a bit less body twist (not roll) in the corners.
No comfort loss, but definitely a handling change.
To rank the braces I have:
rear sway bar
k frame
rear strut
front strut
Someone else may argue that the order should be different, but this is what I thought. I'm not sure on front sway bars, but think that they may introduce some more understeer - happy for someone to correct me on this