Based on my very limited technical knowledge of the mater I would agree with this method. There are plenty of gains to be made throughout the rest of the system so you might as well go down the path well travelled and get a BA/BF turbo. I guess it comes down to what you want out of it and I could be totally off the mark but I would have thought that given our gear ratios, a big meaty torque curve would be the best for a car that weighs 2000kg. If you want ultra responsive, keep your standard turbo, do your intake and exhaust, kick the girlfriend and spear tyre out, loose 15kg and you should be right. Or just steal a turbo of a new Porsche…