can i install the after market header without ECU tune ?

Send a PM to amarpauld...he knows everything ;)

You can if you want. You can install anything without an ECU tune. But you'd yield more power with a ECU tune in itself.

cuz i don't have snow tire ... can't go to RR ...

IMHO, unless you got the header for free, I wouldn't even bother putting it in.

you need snow tires to drive to squamish on the highway?

Nor would I, fuka.
I'm a big fan of the oem manifolds, especially when you're still running the stock turbo. While some top end gains could be tuned in, I wouldn't want to losses down low since the header should shift your whole powerband to a higher rpm.

Aren't the stockers better for retaining heat anyway?

Since they're a heavy cast material, they do retain heat better than a thin walled tube typically used on a header. There's a reason why guys like Cobb use materials like Inconel for their uppipes, and cast inlets for their d/p's. It's all about maintaining heat inside the pipe, and in turn. velocity.

You could always ceramic coat or heatwrap the headers which may not be the perfect solution, but will help in the long run.

One thing headers do well regardless of what setup you're running, is drop weight.

IMHO dont do the header, unless you really know why you need it. There is better $ spent elsewhere. That being said, normally purchased aftermarket headers are not something that you need EM for to safely install (unlike a TBE on an STI, or a turbo, or an intake - the header normally won't radically change any thing forcing you to do EM ast the same time). So your typical "WRX header" from a decent vendor wont REQUIRE tuning to still run safe. However, it is quite possible to get a header that may require tuning, especially if it radically changes the flow velocity and/or requires removal of the front O2. So just make sure of what you are getting. But in any case, almost everyone I know of that has one drops it after a little while...

p.s. hypa the "reason" is sometimes "Manufacturing" explained through "Marketing", ;) there is a whole slew of issues with heat retention, turbos etc. Some places are decent for heat, others are bad.

Bloody marketing people, always telling lies!
:lol:

Velocity and heat retention is like black magic to me, Pat. It seems like everytime I learn something new about retaining heat in the manifolds, how heat aids spooling of turbos, etc, there's always an addendum that goes along with it. Too much heat, not enough heat, just the right amount of heat..... it's easy to get confused.

If you're in the mood to offer some insight on the good, the bad, and the ugly of heat retention, I'd like to hear it.

:)

I found a good article that took a bunch of headers and compared them on the same cars, on the same day.

http://subaru-wrx-sti.com/web/MODS/WRX%20Header%20Test.pdf

it pretty much goes like this

there is a certain point where more energy on the hotside doesnt translate to useful increases in manifold pressure. Think boost creep, or think excessive exhaust back pressure. Think why an EWG yields huge gains on a teeny weeny hotside turbo, but not as much gains on a high flowing hotside. If you are running well within the efficiency range of the turbo (ie. not at the edge of the boost curve), the heat helps. If you are on the edge of the curve, the heat can hurt. I've also seen melted exhaust valves, melted blades, melted downpipes and melted up pipes and alumized turbos.. you get the idea.

I should have also mentioned in my post:

of course, headers should be tuned to maximize gains, but dont worry about putting them on without EM - unless they are 'radical' you should be ok for a while. however, if you are already getting boost creep or something like that, the header may exacerbate the problem.

I found a good article that took a bunch of headers and compared them on the same cars, on the same day.

http://subaru-wrx-sti.com/web/MODS/WRX%20Header%20Test.pdf

I like fast spooling turbo, much more fun then high boost in my opinion :D Gonna keep my stock headers for sure (and the fact I don't have the money to spend on headers :P)

im planning on porting my stockers.... :)

it pretty much goes like this

there is a certain point where more energy on the hotside doesnt translate to useful increases in manifold pressure. Think boost creep, or think excessive exhaust back pressure. Think why an EWG yields huge gains on a teeny weeny hotside turbo, but not as much gains on a high flowing hotside. If you are running well within the efficiency range of the turbo (ie. not at the edge of the boost curve), the heat helps. If you are on the edge of the curve, the heat can hurt. I've also seen melted exhaust valves, melted blades, melted downpipes and melted up pipes and alumized turbos.. you get the idea.


That's some good stuff right there.
What I'm reading is that there's a fine line between maintaining heat and velocity, but also in transferring that heat so it doesn't melt your hardware.

Like Sponaugle says, tuning is all about heat management. That's a hell of a good saying.

;)