it's all about effiency with turbo there will be positive pressure and the idea is get whatever psi you want into your cylinders,and evenly across all cylinders at the same air temp. bigger phleum means less preasure drop in the phleum while smaller fills faster and less air just sitting there. Also while air is entering your cylinder air is also entering the phleum. Rpm is also gonna have a big equation as to how things go not to mention valve timing, size, lift and duration. It's simple to see research goes into it so your homemade hack job probably isn't gonna be better than aftermarket just cheaper(not to mention it has a good chance of hurting performance). Also it depends what RPM your looking to get better efficency at. The change you see in your power depends on the rest of your engine. boost, i/c pressure drop, and a bunch of other stuff. I was also wondering is it better to have 2 boost gauges one after the i/c and bov and one before? the one after would be just for your data loging and keep u informed.