posting to a fellow lgt owner... some thoughts about all you've done. pretty big undertaking none the less. i know i wouldn't have went after a wrecked car but props for going after it; looking fairly good.
you realize though part of why you've got a crap load of carbon build up is not just because you've got a catless set up right? the 100% vent to atmo blow off valve is a really terrible idea on a subaru... the ecu is set up to have atleast 50% recirculated into the system to help with turbo spool and such. so when your car is shifting you're going way right which will cause some detonation into your exhaust. it's pretty harsh on the motor as well as the exhaust system. too unless you've been tuned for the intake you're also throwing your a/f's all over the place. you can tune the system to take the 100% atmo valve but i really wouldn't suggest it.
granted i'm not sure what you're using to tune since you've made no mention of an accessport or anything that i've seen. just some food for thought to help the car along over time. if you want to see what i've done to mine search my name i've only made one thread here and it's on my car.