Originally posted by siueclipse
Im curious, Why do most turbo kits come with only 2" piping for normal size turbos, but when you run larger turbo's.. like the 25g you bump up to 2.5". There must be a reason for it. Im going to call HRC and ask them why they have setup their kits that way.

The same reason that the 1st gen DSMs came with ~2" piping from the factory... the manufacturer found it to be the overall best size to use for the application, for one reason or another. That doesn't mean it's the best size to use, and it doesn't mean it's the only size you should use with a particular turbocharger. We're talking performance turbo tech man, not bolt-on/oem tech. Call them if you want, but I'm sure they'll tell you it's the best size for a 16G to keep charge velocity and flow optimized and that it's based on the stage 2 kit.