I currently have the NP axle back with 5" mufflers on my 2011 WRX 4-door. I contacted Nameless Performance about completing my system to a full turbo back and they sent me dynos that showed substantial gains going from stock exhaust to just a cat-back. I know this is a debated topic with those saying there are no gains to be had from upgrading the mid/Y pipe and those that counter with the restriction argument. However, these dynos do show gains and I'd like to share them with you. I'd also like your opinion, based on these dynos, proven numbers, and first-hand experiences if getting an upgraded mid/Y pipe would be worth it. The first is torque, the second HP on an STI with the mods listed.