thats the thing with skylines especially with gtr's and gtst's, they have been talked up so much and rated so highly that when u get in a gts, it seems a total let down. i know what you mean by how they feel gutless (but at the end of the day its a 2L or 2.5L twin cam)
down in the low rpms i find my car to be totally crap - but when i start getting around 4000rpm onwards till about 6000rpm it really picks up... its so chunky up at high revs and i love it.
it doesnt have that push you into your seat feeling, but it just pulls and keeps pulling and sounds like a dog with chilli on its nuts.
just depends what you want really... handling? styling? power?
from there you can decide - what would be a good base to start on. then when u find that point where your comfortable with what you have - go have fun.