It would help you to learn to plot compressor maps so you can read how efficient they will be. The GT28R turbo is a really poor match to the VG30 motor, it will be extremely laggy. If you go to TurboByGarrett.com and download the catalog you'll see the compressor maps. After understanding them you'll see how bad a match the GT28R is and how the GT28RS has a much more compatible compressor for our engines.