Agree w/ Gene and K9Intender: play nice.
Turbo V6 vs V8: my take is not on which one is faster 0-60 but the general trend in automakers shying away from V8s. Think this has to do w/ fuel efficiency (or at least the optics of it) and increasingly strict emission standards. The flame-throwing (just kidding) part of my argument is the engine sound. Excluding the effects of muffling, NA engines sound the best (air-cooled in particular)!
Regarding Kia K900 marketing in the US:
1) There was never any question K900 is a great car. The challenge is marketing hi-end autos in a mass-market shop. The impact is not just on K900. Care to count how many Cadenzas you see on the road?
2) After the initial euphoria, dealers may be reluctant to stock K900s since they're not selling and thus put a drag on floor plan financing. And then spiral goes down from there. No inventory = no buyer interest (after net-browsing, potential buyers wants to go to showroom to feel/touch the car; and no car = no sale prospect).
3) Kia may not care how much the K900 sales in the US; since the main battle is fought in Europe and Asia for this car. Worst case this becomes a halo for Kia in North America. Kia will simply coerce US dealers (more precisely the selected few eligible to sell K900s) into ordering for showroom and there aren't much dealers can do. So the dealers will play nice and each order 1 at most 2.
4) I suppose somewhere along the line Kia did a cost/benefit and include it is not worth the investment of a premium channel like Hyundai did w/ Genesis. This Genesis experiment is still out. While I see quite a few G80, the truly hi-end G90s are still a rare sight, albeit not as rare as K900. I think the Genesis bet will ultimately become successful. It just needs a full line of automobiles (small-mid-fullsize sedans and SUVs, w/ a 2-door premium thrown in).
5) How to resolve the problem that Hyundai/Genesis/Kia have poor resale values, now, that's the big question...