Supporting mods as in downpipe, intercooler, injectors, pump,clutch engine managmenet system, and engine internals required to run such boost.
Trust me go for the 15gs and run the pump gas, I run race gas all the time since my car even at low boost runs badly on pump. depends on what you're looking to build I guess.
What are your current mods????
best to start of with all of the basic supporting mods.