0.96 is too big for our motors. No wonder its laggy as hell
Drop down to a 0.82 ball bearing unit and you'll see/feel the difference immediately... Guaranteed!
The GT35R comes standard with the 4" inlet 2.5" outlet compressor housing too, so your existing intake plumbing should mate up without any major mods. You can of course order them with a 3" inlet, 2" outlet too.
I'd be interested to know the diameter of the primaries on your custom headers. Too big, and that also affects spool
Btw, can you actually get a 0.9 bar spring for the OEM waste gates?