[BADDASSC6]

I would recommend the following mods:

magnus makes a sheetmetal intake manifold for the subaru WRX and STI. That will be money well spent. The plenum is much much larger in volume. The runners are shorter and wider.

After that I would try ordering a ported set of heads. Your heads have a lip on one edge of the intake valve to promote turbulence and better fuel mixing. This helps with torque and emissions. If you are not happy with the manifold try this out.

This is all power that can be had with out increasing the boost and minimizing the added strain on the motor. Frankly, I believe in building up hte base airpump before killing it with a bigger turbo.

[Vettezuki]

Originally Posted by BADDASSC6

I would recommend the following mods:

magnus makes a sheetmetal intake manifold for the subaru WRX and STI. That will be money well spent. The plenum is much much larger in volume. The runners are shorter and wider. . . .

You read my mind. I thought there must have been some kind of aftermarket intake. That looks like a helluva stout piece too. I'm a little surprised there aren't aftermarket heads a la A.F.R.

[BADDASSC6]

You can buy aftermarket heads that are stock cast heads workedover, but no completely new castings.

I personnally don't know of any aftermarket head manufacturer import or domestic that make aftermarket cast heads for cam in head motors????

Has anyone else heard of any?

[SeanPlunk]

Originally Posted by BADDASSC6

You can buy aftermarket heads that are stock cast heads workedover, but no completely new castings.

I personnally don't know of any aftermarket head manufacturer import or domestic that make aftermarket cast heads for cam in head motors????

Has anyone else heard of any?

The SOHC Mustangs have aftermarket castings available. Here is an example.

[WagonSleeps]

^^stout piece indeed, I agree with everything said above, had a recent slip up today and pending more power or even possibly parting out and trading in the car...hate to do it but.


As far as built heads and intake manifolds....Cosworth, Crawford are 2 popular manufactures that provide these mods

expect to pay $$$$$$$$$$$$$$$$.

he Cosworth Subaru High Volume Inlet Manifold is cast from aluminum featuring large tapered runners with radiused inlets for improved air flow. Plenum volume has been substantially increased and tuned for power. Engineered for easy installation and is the key to making big power.

Cosworth intake manifold flows an average of 478.5 CFM per runner and the stock manifold flows an average of 421.25 CFM per runner. That is about a 13.5% increase over stock. These numbers were measured at 50 inH2O on our flow bench (some people use 28 inches to measure, but 50 inch is a motorsport standard.

The Cosworth manifold made 12-15 hp above 6000 rpm with no sacrifices in response or low end torque on a stock 300hp engine. Same boost level.
As boost levels are increased over stock levels, the power gains compared to the stock manifold will be even higher
■■ Substantially increased plenum volume
■■ Large, tapered runners with radiused inlets
■■ Tuned plenum volume and runner length/taper
■■ Over 10% increase in flow
■■ Integral vacuum manifold for connection of brake booster, boost gauge, MAP sensor, boost controller, etc.
■■ Will work with standard or forward mount throttle body configurations
■■ Stock throttle body location for compatibility with most aftermarket FMIC kits


I see lots of motor builds from other subaru owners who go Hybrid and tend to still use their 2.0 or 2.5 stock heads reason being for less power....

Built heads, around 4200-5k....

[SeanPlunk]

Originally Posted by WagonSleeps

^^stout piece indeed, I agree with everything said above, had a recent slip up today and pending more power or even possibly parting out and trading in the car...hate to do it but.


As far as built heads and intake manifolds....Cosworth, Crawford are 2 popular manufactures that provide these mods

expect to pay $$$$$$$$$$$$$$$$.

he Cosworth Subaru High Volume Inlet Manifold is cast from aluminum featuring large tapered runners with radiused inlets for improved air flow. Plenum volume has been substantially increased and tuned for power. Engineered for easy installation and is the key to making big power.

Cosworth intake manifold flows an average of 478.5 CFM per runner and the stock manifold flows an average of 421.25 CFM per runner. That is about a 13.5% increase over stock. These numbers were measured at 50 inH2O on our flow bench (some people use 28 inches to measure, but 50 inch is a motorsport standard.

The Cosworth manifold made 12-15 hp above 6000 rpm with no sacrifices in response or low end torque on a stock 300hp engine. Same boost level.
As boost levels are increased over stock levels, the power gains compared to the stock manifold will be even higher
■■ Substantially increased plenum volume
■■ Large, tapered runners with radiused inlets
■■ Tuned plenum volume and runner length/taper
■■ Over 10% increase in flow
■■ Integral vacuum manifold for connection of brake booster, boost gauge, MAP sensor, boost controller, etc.
■■ Will work with standard or forward mount throttle body configurations
■■ Stock throttle body location for compatibility with most aftermarket FMIC kits


I see lots of motor builds from other subaru owners who go Hybrid and tend to still use their 2.0 or 2.5 stock heads reason being for less power....

Built heads, around 4200-5k....

WOW, those intakes are trick. What happened with your car? After everything you've done to it you can't give up now

Oh, and 4200-5k for built heads

[Vettezuki]

Originally Posted by WagonSleeps

^^stout piece indeed, I agree with everything said above, had a recent slip up today and pending more power or even possibly parting out and trading in the car...hate to do it but.


As far as built heads and intake manifolds....Cosworth, Crawford are 2 popular manufactures that provide these mods

expect to pay $$$$$$$$$$$$$$$$.

he Cosworth Subaru High Volume Inlet Manifold is cast from aluminum featuring large tapered runners with radiused inlets for improved air flow. Plenum volume has been substantially increased and tuned for power. Engineered for easy installation and is the key to making big power.

Cosworth intake manifold flows an average of 478.5 CFM per runner and the stock manifold flows an average of 421.25 CFM per runner. That is about a 13.5% increase over stock. These numbers were measured at 50 inH2O on our flow bench (some people use 28 inches to measure, but 50 inch is a motorsport standard.

The Cosworth manifold made 12-15 hp above 6000 rpm with no sacrifices in response or low end torque on a stock 300hp engine. Same boost level.
As boost levels are increased over stock levels, the power gains compared to the stock manifold will be even higher
■■ Substantially increased plenum volume
■■ Large, tapered runners with radiused inlets
■■ Tuned plenum volume and runner length/taper
■■ Over 10% increase in flow
■■ Integral vacuum manifold for connection of brake booster, boost gauge, MAP sensor, boost controller, etc.
■■ Will work with standard or forward mount throttle body configurations
■■ Stock throttle body location for compatibility with most aftermarket FMIC kits


I see lots of motor builds from other subaru owners who go Hybrid and tend to still use their 2.0 or 2.5 stock heads reason being for less power....

Built heads, around 4200-5k....

Cosworth? As in the truly great, glorious, and magnificent British engineering firm and engine builders? This is OT, but they may be the engine suppliers for the new USF1 for next year.

Yes, you pay mad scratch for bits at this level.

Does anybody put 2L STi heads on your block, assuming smaller combustion chambers and slightly higher comp? Common trick on NA LS motors, probably doesn't make a lot of sense on these Boxer motors; just curious.

[Leedom]

Glad to see this thread has finally calmed down. I thought I was going to have to give you guys a timeout!!

[Vettezuki]

Originally Posted by Leedom

Glad to see this thread has finally calmed down. I thought I was going to have to give you guys a timeout!!

FAHQ Hippie. My Vette owns all Mustangs! Especially Yellow Mach 1s! Ha!

Just kidding. Somewhere in a photo album is a picture of me when I was about 3/4 . . . chill'n with a can of Bud and a full Jew Fro. Priceless.

[WagonSleeps]

^^ Yep Cosworth it is my friend!


They have been IMO and many others as well. They treat us well with quality stuff. The shops actually waiting on one of the 1st Longblocks for the STi thats being swapped into an 08 sti . Cosworth has shown us nothing but good things.

As far as i know or heard, i havent seen too many 2.5L putting STi heads onto our WRX. Plus to be honest, certain years and the way people mod their wrx's and sti's. have a tendency to run low compression checks. Thats the reason being tunes on our cars are so crucial. Too many stories about engines going cause of cars running too lean from not being tuned etc, long story short F'in your car up. hahaha.

Heres how the STi / WRX models went year by year.

02-05 WRX NON STi's came with 2.0 liter turbos.

04-06 STi came with 2.5 liter turbos using vf39 turbos with 560cc STi pinks. (06 years got the 565 blues like the 06-07 wrx and sti's did)

06-08 WRX non sti came with TD04 turbo(tiny tiny turbo, yes more tiny that the STi ) with 565cc blues. And the 08's and up got the LGT 5 speeds included, finally did something about the 5 speed issues.

07 STi came with new VF43 (basically same as vf39) as well as 565cc blue injectors.

08 STi has a tad bit bigger VF48 turbo using the same 565cc injectors.

09 WRX comes with a new vf52 turbo with 565cc injectors as well if im correct.

All the VF series turbo push around the same whp using full turboback, fuel pump and tune.

As far as horsepower gains, it seems as if the 06-07 wrx's gain abit more torque than sti's do. possibly from the 5 speed ratios compared to the 6th. My dyno sheet is damn near similar or exact to what youll see on a sti since we have identical 2.5 liter engines. As far as using STi parts, might as well go aftermarket. Equal length headers, Up-pipe, Intake manifolds, and headwork, all good things to gain some ponies yet a pretty penny.