i really think it can.

when i got a 13.4 i was on 17" wheels, had a 2.0 60ft(yes..i suck at life...but it was one of the first times i've been to the track), a full interior and i was untuned. When i say untund, i don't just mean there's more power in the car..i mean that with the UTEC built in knock sensor it will pull timing to compensate for the detonation. So as i'm going down the track the car would start to pull(the CEL light would flash as a sign of detonation) and the car would back off...than it would start to pull..and back off again.

So if i can cut a 1.8 60' which i had done before, thats good for a 13.0-13.1(if 1 down low is good for 2 up top), if i can get the car tuned...i might be able to squeeze out more power but atleast it won't be pulling back the timing and studdering going down the track. I hope thats good for a .1 second descrease, and if that STILL doesn't do it, i'll put 16"s on the car and remove somethings from the interior. (the passenger seat, the spare tire, the back seats) but i don't think that will be necessary.

sure it's a 12.9...but it's still a 12 on intake, exhaust and UTEC.

A header for a WRX will cost a butt load(probably as much as a good turbo back system) and i've heard they don't really do much to justify the cost.