Jay's kit is not HPA. He pieced together the conversion himself, and did most of the work himself or with a couple of helping hands, and most of the work was down in his own garage.
And trust me when I say that down low, the R has not lost any of its N/A sound... Having ridden in it several times (he still won't let me drive it... :p ), the thing is insane when it hits boost!! once the clutch slipping issues have been sorted out, the R will be in its element!!