Tested out the Turbosmart USA IWG on our 2015 Sti today and it works really well. We first tuned the car with the stock IWG and just swapped on the Turbosmart IWG with no changes made to the tune. Both IWG are being controlled by the stock EBCS.
The Turbosmart IWG is running a 7 lbs spring.
The Blue line is the Turbosmart IWG and the Red line is the Stock IWG.
You can see that boost comes on a littler faster but also over shot the target boost table causing the boost dip. With tuning that will be no problem to tune out. But as you can see boost is holding higher in the upper RPM's with the TS IWG over the Stock IWG. We think this IWG paired with a 3-port EBCS will be awesome combo. We will be trying that out next.