Header (stock vs after market)
 

Okay Ive personally seen Nick's Dyno #'s But Ive just talked too Cobb/Modern garage and they are saying they will not create the heat that the turbo needs too spool properly WTF :huh: I dont know what to do I really dont care about the way the car is going to sound I would like a little more tork Chris at modern(Cobb's dyno tunners) said that the boost come on later to :mad: I have already committed to a set of headers on I-Club GT-Spec2 :(

I honestly don't agree with Cobb's assement here. I think that it will give some benefits. We've seen Nick's car with these exact headers on it, and it puts out better numbers then without.

If you are worried about heat loss, you could always try wrapping them, but I don't think that is necessary.

There are some tuners on NASIOC who say that headers are a waste of time, and others who swear by them. All I know is that the GT Spec IIs made a huge difference on Nick's car. Isn't his the first stock turbo STi to put down 300+ ft-lbs on Nate's dyno, when others with the same mods but no headers are around 270 - 280 ft-lbs. Dyno numbers don't lie (especially them new fangled road dynos).

I have a set on the way too, mine are sold in Japan as Tomei, slightly different design. It will be interesting to see the results.

BTW I read a while back on NASIOC the guys from gruppe-s found that coating/wrapping headers to retain the heat got back all the spool that they lost. Definately consider doing that!

What Nick said. There are a bunch of people out there, tuners included, who have just now accepted some of the initial EJ20 limitations; cheap intakes like AEM's don't work on stock cars, headers on a stock turbo are pointless, etc.

These theories are being proven wrong repeatedly on the whole new animal the EJ25 is; you've got way more exhaust flow, so the heat reduction from unwrapped headers is more than offset by the flow rates going way up. Well designed intakes like the Injens work well with a tune, and some of the larger setups like the Perrin big MAF setups are the way to go when you're running larger injectors and can scale accordingly.

To put it simply there's alot of people that are just now catching up with the conventional knowledge that some of us picked up from people that have been tuning Subarus in other markets for way longer than they've been available here.

Like Nick said, common knowledge about cars be damned, we've seen headers and intakes make huge differences on the 2.5's. Of note is that Nick's car actually exceeds Slowboy's expectations for the GT30-12 with the generic "intake and headers" allowance, but the particular setups we're running are recommended for a reason :D

yeah just like the under manifold hose makes no difference.

i have run headers too and i have run without them.

basically take your motor and look at it like this.

NA + Turbo

the NA side of your motor will give you many good lovins for getting headers.

The turbo side of your split personality will say where the hell did my pressure go ?

fact of the matter is. if you increase flow through diameter changes. you loose pressure. if you change the material you change the heat scavenging effect. so youre screwing yourself twice. even if you coat the headers AND wrap them, you cant get it all back. however. im not saying the loss to gain is 1:1 ratio.

there maybe 15 negative side effects and 1 positive effect. doesnt mean its an overall negative mod.

you find one thread on the internet or one person saying one thing. ill find 10 others that say the opposite. and noone knows anymore who is credible.

when i moderated a sportbike site we caught one of our vendors registering fake names and saying duragatory things about other vendor's products. also he would say how good his own products were.

needless to say. do what you want! its nice to have imput. just keep in mind who is credible and who is not. <3

Headers don't necessarily increase diameter or reduce flow if the designers know what they are doing.

Headers, like all parts, can be engineered to give you what ever you want, and the GT Spec 2 headers are ones that help increase low end torque. Headers can be designed to give you more low end, more high end or more midrange. Cheap headers, or headers designed by people that don't understand all the variables (flow/heat/etc), will invariablly be awful for your car. But well designed ones can help you in a lot of ways.

To say that headers on a turbo car has more negatives then positives is pretty ignorant of the whole picture. Most headers that came out for the Subaru early on were poorly designed, so lots of people latched on to the idea that headers for Subarus are bad. They aren't bad, if designed properly.

Another caveat is that you will need a reflash to fully take advantage of well designed headers. I don't think Cobb AP has this functionality built in since they seem entrenched in this idea that headers reduce performance. Protuner will probably change that when it comes out.

if youre reffering to what i said thats not at all what i was trying to get across. what i was trying to say is any mod can have 468721648 negatives and 1 positive effect. but that doesnt mean that the negatives out wiegh the positive effect.

and most headers that i have seen, are designed to flow more volume of air, not keep up velocity. not saying that other ones arent out there, just saying what i have seen.

For sure, I get a little into it on the header issue since so many people seem to think they don't do anything when in fact the good ones do help

For what its worth, I mostly agree with you; I wouldn't touch most headers because they are designed poorly for Subarus.

i wouldnt wrap them.. simply because it could cause a fire in the engine bay. You might think, oh it'll never happen to me, but i've seen it happen to someone's STi down in california. I'm sure it'll do something as far as creating more power though.. you figure, MORE FLOW = more power.. reguardless.

If Subaru engineers can design cast exhaust manifolds that flow decent. I don't see why aftermarket engineers can't design a header to do it better.

As mentioned, there were so many early designs of poor quality, it might have given headers somewhat of a bad rap for Subaru's. IMO, creating a quality, well designed header, that actually performs, is a work of art in itself.

Try trolling around on e bays 500+ exhaust auctions for a WRX and see some of the junk people are building to make a buck. The old addage is true. You get what ya pay for.

its really all about tradeoffs. which you want more?

flow?
velocity?
heat scavenging?

everything is a tradeoff in life.

The gt spec II header clearly made a difference on my car. They are jet hot coated. They added crazy low end torque with the VF-39. I gained 10 whp and 33 '# of wtq. Max torque was 310 '# at 3750! While many people are not a fan of the sound. The gained torque, in my opinion, was well worth it.

get it - jet hot coat it - slap it on - be happy :)