Drilling Ports through Runners 1 and 4 will aid in better collection and therefore the more equal relief of Boost pressure. I will tell you more is the key word in the last statement. You could drill it as much as you want and if you were to flow bench it you would not see nearly as good of results as you would on a custom manifold or a full race. I say flow bench instead of dyno because with the use of the dyno their are many variables in the equation that could effect numbers besides the changing of manifolds so this form is not as accurate as flow bench. I would recommend taking a Megan and cutting a cross section in the collector and then welding in a pipe into that collector cross section this well give you better results for more equalized boost relief. Take a look at full race's design, I am not trying to jump on their bandwagon but their product works so you can take some of their design elements and apply it to your application.