I have the IPD plenum and the Softronic tuning with a Milltek catback. I installed the plenumn, exhaust, and the tuning in that order. Several months in between each. I didn't notice a huge difference with just the plenumn, but when I installed the Milltek the car really woke up. It seemed like you needed to improve both the incoming and exiting flows at the same time. They really seem to work well together. The tuning was just gravy on top at that point.

__________________
Nov 16, 2007 build:
'08 CS Midnight blue metallic--6 spd
Black sport seats, Delete model designation
Fire extinguisher,Floor mats, Sport steering wheel