I just fitted the Garrett 2860-7s (note 7, not 5), which after much research I came to the conclusion were the equivalent of GT-SS. I would have gone the GT-SS if it wern't for the garretts being much better value. Now these 2860-7s are confusing because acording to Garrett's website they are "OEM on Nissan RB26DETT used in Skyline R34 GT RN-1" - so I assume they are what's commonly refered to as N1 turbos. And the 2860-5s are roughly equvalent of HKS 2530s, which are another level up from GT-SS, and not great for mid range... as far as I know, correct me if I'm wrong.
So anyway, my hoopty (R32 GTR) is much nicer with the new turbos - thrust arrives a tiny bit later than stock, but still a fat mid range. But is crying out for the appropriate supporting mods such as a computer of some description. Anyway, I'd take you up on that six pack, except I'm taking off overseas in a matter of days. Good luck.