SF kits is the best kit but you will wait ten years before they ship it to you. Turbo XS is best route i think... and C2gas is a guy from hungary or germany, can't remember which but he has sold one kit. He is not a shop owenr or anything I dont think. I would count that one out.
From Hungary. AND yes we did 1 USA GT wioth st2 kit pushing 270whp, but a plenty european, from Germany, Netherlands, England, and our GTS kit is now to be finished as we are doing a GTS st2 kit with ~350-400whp (BTW this is also from an American soldier). Thats why we started the tranny project cos that needs it. Actually we did the first strongets GT Turbo. Yes we are oversee But prices competetive even with shippin. And we DO have kits on stock.
We have coupleof other projects as well.
So Where do you get your "knowledge"? Visit The other CELICA Forum in the forced induction and ask around. You will have real answers there about kits.