Those boxers love a free flowing exhaust though, could make good gains there if you haven't done anything yet.

 @badbadleroybrown: hence the 3" bellmouth downpipe to cutout... I know the stock axleback is restrictive when the cutout is not open, but O figure if I want to do racecar things, I'll listen the racecar sounds... Otherwise the stock axleback makes responsible driving much more tolerable.

 @swan3609: wish I still had my 07 WRX wagon. A Cobb intake, full Perrin exhaust, larger top mount ic and stage 2 tune made that car fun around town. Then the list of mods went crazy and a bad tune took out good old no.4 piston. Wife convinced me to sell it. Stupid me should've just rebuilt the motor. One of my biggest regrets

 @dchill: That's what I am hoping not to do with this XT Forester. Subarus are fickle about their tunes.. I have already done the bigger turbo, intercooler, full exhaust and other supporting mods.. Along with a 6speed Trans, sti steering rack and sway bars, sti seats and some other goodies.. And I actually have a spare 257 longblock if/when I blow mine up, but I still would like to avoid that if possible.

 @swan3609: best thing is make sure never to lean it out and do forged pistons. The stock cast pistons are garbage. #4 piston because being at the exhaust gets the most heat make sure you have an AFR and boost gauge
What size turbo did you go to and did you do a larger TMIC or front mount ic?
Since you have the spare block you should build it up with forged pistons and rods, depending what year the extra block is even do a crank

 @dchill: I am just on a STi takeoff VF39.. Bigger STi intercooler, catless uppipe and downpipe, I monitor AFR, Boost, Temps,
Knock, etc.. Doing TGV deletes and intake and a few small things before I get it protuned. Would be good to get off the cobb OTS tune and get proper tuned.

I am planning on splitting the 257 and doing pistons and rods.. It came with my 6speed, I was told it ran great when pulled, but I figure I might as well break it down and make it fresh and make it bullet proof for the little 300hp I am shooting for..

 You gotta build that block! That's the best way to do it... makes it so much easier to do everything without having to go step by step. Just build it up and drop it in. That's gonna be rad... 300 horse is no joke in such a small vehicle.

 @badbadleroybrown: my current shortblock is the same as the STi 257 on my stand.. I just don't have quite as good flowing heads on my 255.. With my current setup, I am probably 270hp and could probably hit 300hp with a proper protune.. A built motor would just be much more reliable at this power level.


I have built a few air cooled flat 4 and flat 6 airplane engines, but if I do a full build on the EJ257, it's going to be blueprinted by a local builder, I am blessed with a few local experts that are nationally renound Subarus experts.... Like they are currently building a 900+ whp twin charged STi.. Haha my little car is a cake walk for them.

But your right, 300hp at the wheels in a small AWD car is fun..

 Jesus... I couldn't imagine what s 900hp subi would be like!

 @badbadleroybrown: absolutely insane I am sure.

at idle, it's pushing 6psi of boost from the blower... It's silly.. But it's also probably a 90k car too. Haha

 @swan3609: Man that's crazy, I bet that is stupid fun to drive.

 Lift and tires and already bought and on the way... the front coilovers are on back order from Fox until the 7th. Then I've got BFG AT/KO2 ready to go, 285/65x20... basically 35x11.5.

Thinking about the fuel map but I'm not sold yet. Supposedly could bump me all the way up yup 475hp and 495lb/ft but at that point it'll start being a little less driveable around town, less fuel economy, etc... Intake and exhaust are kinda free upgrades to performance all through the rpm range, but you gotta make trade offs when you start getting into the mapping. Not sure if I want to go that route when, realistically, it's already all the power I need.

 @badbadleroybrown: with modern day cars the intake and exhaust do very little unless the computer is mapped for it.

 @USMC: No... Not true. The computer is constantly adjusting for air temperature and volume on the intake side, increase in airflow leads to any increase in fuel to prevent it from running too lean... and exhaust side, pulling the restrictive stock exhaust does wonders, especially at rpm. You can definitely get further gains with a tuned fuel map but you can still easily pick up a few percent gain on either end without it.

 @badbadleroybrown: 100%. but those chips are not much more expensive than that cold air intake. although a buddy with the same truck as mine did the air and chip mod has more HP, but his fuel economy is f*cking terrible.
choices choices. my next investment is an addicitve desert designs pre runner bumper.

 @obee1: Yup, that's the thing, once you start changing maps and tunes out becomes a game of trade offs. I don't really need more power but I appreciate still getting 19mpg...

Those bumpers look damn nice, pricey though. I've been thinking annoy replacing the grill with something that'll hold a light bar but I don't know if I'll mess with the bumpers. Once I start down that road, I can see myself blowing $15k and winding up with a 6" lift, 40" tires, desert bumpers, light bars, and a truck I don't enjoy driving around town as much. Its a slippery slope lol.

 @badbadleroybrown: sounds right. if you look at my truck i didnt get fog lights, and the bumper is big and plain. a pre runner would also compliment the lift kit, so i'm pretty sold on the idea. but spendy AF!
i hate driving at night, too many animals on the roads out here. so no light bars in the plans for me. no need. besides the roof mount light bars make a fair bit of wind noise at speed.

 @badbadleroybrown: I will tell you first hand you are wrong. Stock PCM's will only adjust for so much in a certain set of perimeters. The mfg says here is the air flow and exhaust we have and here is the maximum amount t that it should need to be able to reach stoichiometric fuel ratio. When you change air intake and unless you did a full exhaust eliminating the cats it will push what the stock PCM can adjust to to factory limitations. Hence the reason for chips. But what do I know 9 years as a GM mechanic 8 at a speed/dyno shop.

 @USMC: You actually can't tell me anything "first hand" since you have literally never seen, been in, or driven my truck... but I can tell you, first hand, that before these modifications it wouldn't break loose the rear tires by just standing on the gas leaving a stop sign... it will now easily spin the tires just stomping on thr throttle and will chirp the tires going into second gear now. So, actual first hand experience says you're mistaken.

You seem to think that adding 30hp to this engine is a significant increase... That's not even 10% increase combined, it's about a 7.5% improvement. That's an entirely realistic increase and pretty much to be expected on every vehicle out there by removing the restrictive intake and exhaust. If I was looking for 20 or 30% improvements, then yes you're right, you have to move beyond the factory computer at that point... but for sub 10%, sorry marine but you're mistaken.

 Like I said.. It was making 6psi boost just rolling along at idle cruise.. I am sure it was silly.. But that's also so far out of my price range that it's not even fair to compare.. Haha