Look, if you're looking to get easy power out of your 15+ STI. The Cobb Accessport is your first stop. You can make great power with no other modifications and then as you do upgrade your downpipe, intake, and more you can switch MAPS with ease.
The most complete Subaru tuning solution on the planet
The Accessport is the world's best selling, most flexible, and easiest to use ECU upgrade solution for your Subaru. Unlock power hidden within the vehicle by replacing conservative factory settings with more aggressive calibrations. Follow our staged upgrade path with pre-loaded Off-The-Shelf (OTS) maps or use custom mapping for any modification level. It's the last engine management solution you'll ever need.