Definitely a beautiful piece. I think you'd like get quite a few bites if it were in the 3-3.5k with tune range, but 4200 (especially if that doesn't include tuning) for 15-20hp and some beautiful noise is, in my opinion, a bit hard to swallow when a SC setup isn't that much more, and offers more than 10x the power gain.
I think there'd probably be some market for folks that really wanted to stay NA, and really wanted the wonderful induction noise. Personally, I'd find nearly 5 grand with a tune rather difficult to swallow, though hobbyists of greater means that really didn't want to go the FI route might not feel the same way.
'08 Black Saphire/Black Z4 M Coupe
RIP Gretta: Blue Water/Lemon 135i. Died to save me.