hey wogan, i was in your situation a long time ago.
personally i dont like the hks because its only a 3" cat back, where as the kakimoto is a 3.5" catback.
i would strongly recommend the 3.5 if u are planning some serious mods later on. if not then the hks is your exhaust.
because the way the hks is designed is it very very quiet on idle and cruising, but i must warn u its one of the exhausts that have the wet fart exhaust noise....rather then the deep growl a kaki has.
if you want a nice note wen u "fang it" id get the kaki
but at the same time the hks will not drone or get you into shit with the epa, being very below the db limit.
id go with the kaki personally, 3.5" exhaust = more hp + you get the cool titanium finish (JDM yo =D )