SteamSpeed STX 67 for 2015 WRX
Here is a good dyno result of a SteamSpeed STX 67 on pump gas done at Bren Tuning with a before and after, green being before, and red being after. Obviously there are gains everywhere. You can see their post on NASIOC here. The short of it, the customer go a 85+ WHP and 70+ WTQ gain on pump gas!
Here is a standard STX 67 for 2015+ WRX tune at COBB Surgeline. Unfortunately it does not have the before plot, but it was a 60 whp gain on pump gas. This car had a 3″ turbo back, intake, and front mount intercooler. It was tuned at COBB Surgeline. We have to give these guys at COBB Surgeline props. This customer was initially impacted by the wastegate flapper defect a few units had from the first production batch. The guys at COBB took the time to correctly diagnose the wastegate problem.
SteamSpeed STX 67+ for 2015+ WRX
Here is a nice dyno plot comparing a fully modified 2015 WRX without the SteamSpeed turbo [green], then with the SteamSpeed STX 67+ [red]. This with some ethanol blend, around 50%. This was tuned in Utah at FNP by Jessie. It looks like about a 100+ WHP gain and 65 WTQ.