I've heard that a v6 engine would need to be twin turbo charged to be CARB legal so maybe running off only one bank makes it CARB legal and it is also cheaper than the twin turbo setup.
1999 3.0L Cougar: 220fwhp and 200tq
2003 VW Passat W8 with 4 Motion AWD
http://www.cardomain.com/ride/300644
PM for intrest in 3L SVT Contours, 3L swaps into your current car, Prepped 3L engines, or anything 3L related.