Subarus (or at least most of them) have flat 4's so technically they're headers, it's just a 2 into 1 when you hit the turbo That said, most of them are once solid piece, but technically...

Anyway, sounds like a pretty decent run. What year is your STi? What TMIC and how much boost are you pushing?

 

i like flat-4's there torquey lil motors and they sound awsome after a couple bolt-on's

 

My year is 2005... I have a TurboXS TMIC and I'm running 22.5psi on race gas.

 

Are you still running all stock internals? That's quite a bit of boost on a stock EJ257. I'm surprised you can squeeze 22.5 lbs out of a VF39.

 

random alphanumerics

 

EJ257=EJ series motor (horizontally opposed 4, all based on the same external dimension/mounting point casting)

25=2.5L

7, the extra thing they toss on to designate it not a regular EJ25 that goes into the 2.5 RS (257 is a semi closed deck block)

For instance, my Subie has an EJ22T- 2.2L turbo block (fully closed deck as opposed to the EJ22 which is open deck).

VF39 is the stock STi turbo.