This power chart should obviously only be used as a guideline for turbo selection. Check back on BorgWarner's EFR site in the near future for an extremely in depth turbo sizing app. You forum nerds are going to have plenty to argue about when that's released.
Did you know that BorgWarner is currently the largest OEM turbocharger supplier in the world? The BW turbo brands also include BorgWarner, KKK (Kuhnle, Kopp & Kausch, not the cone heads), and Schwitzer. Despite being as big as they are, BW is planning the release of the Series EFR turbos designed specifically for the performance aftermarket and racing. For the past year, Brock (aka Brockstar) and his team of engineers and techs have been hard at work developing the EFR product line. This is extremely fast for a company the size of BW with very stringent design and manufacturing standards. BW isn't a 5 person shop that copies a Garrett compressor wheel, rescales it in CAM software so there's an infinite amount of trims available, hogs one out of aluminum bar stock on a CNC machine and then proceeds to stuff it into virtually any compressor housing without compressor or turbine mapping (let's not forget about giving these hogged out turbos nonsensical names while they were at it). BW products must go through extremely stringent OEM style durability testing and multiple validations before product release. So a complete line of turbochargers released in about a year is actually light speed for a company the size of BW.
Finish the article at motoiq.com