2008 liberty GT Spec B
Top graph is new billet TD05-18G turbo, TMIC and associated minor mods & tune. Lower graph is original VF4x series turbo and Subaru tune (thin line) and same turbo retuned (thick line).
All of the above tunes have high quality 3" dump pipe ceramic coated onto OEM cat back. Add approx 5% on figures above assuming full 3" turbo back.
Best mods are suspension first. Sways, decent springs. Strut bar top n lower control arm. Learn to drive it with some power. Short shifter makes things easier.
Then start on the "how long is a piece of string" power quest ... The above runs 13.7 but I'm sure if Dougie was driving (he launches cars better) it be <13.5 seconds on the 1/4.