meshmesh, those overlaid power curves are awesome So much extra meat under the curve, you should be stoked :)
As for the extra 500rpm of lag... It doesn't sound like much, but you can really feel it can't you? To offset this, I suppose you can alter your camgear timing and sacrifice a little top end for more mid-range urge...
Also, look into camshafts. I have Tomei 260/260 PONCAMS, but I have a feeling I should have gone for the 260 IN/252 EX choice, after reading up on the Mines R34 GTR... That will give you a little more response too...
Looking great!!! Hopefully I can get my car built soon and post up what GT-SS turbos can do!