legacycentral bbs

so i have a set of headers equal length that are sitting under my desk. the uppipe for the header is only 1.75 id i think.

also on my desk instead of under it is an uppipe with a flex section and all the bungs for the wrx, one of which sill needs a plug. this pipe is about 2.25 id.

so my delima is which one do i use.

i know that headers will move my torq curve over to the right giving me more top end but taking away spool. another porblem is that they both are stainless so they loose heat easily, effecting spool further. coating the uppipe will cost only a few bucks when the headers will cost upwards 250 dollars to coat. i porbaly wouldnt have to coat the uppipe but the headers i would.

so i ask of you. which one should i use on my car.

how do you feel about the burble?

i think you mean that the equal length will make it ricer sound and if that is what you mean yes im very fond of the burble

then do the uppipe.

where will i see the gain in the uppipe though, all the way thorugh the powerband or just up top

Get a stock WRX header.

That way, you get rid of the cat there, but don't lose the burble. I LOVE the way mine sounds at the front. Now I just need to get a cat-back for out back......

Contrary to beleif, a header will not make your car sound like a Honda, trust me.

You might find some upper HP gains, but probably not if your still running the stock heads. No need to just do the up pipe though. Your factory one already has a flex joint, and no cat as you know.

IronMonkeyL255 wrote:Get a stock WRX header.

That way, you get rid of the cat there, but don't lose the burble. I LOVE the way mine sounds at the front. Now I just need to get a cat-back for out back......

We don't have a cat in there. The drivers side WRX Manifold has the same part number as the stock Turbo Legacy manifold.

The Turbo Legacy only has 2 cats stock. Downpipe and Midpipe.

The WRX has 3 cats stock. Uppipe, downpipe, and midpipe.

Neither of us have cats in the header.

the factory uppipe doesnt have a flex joint. that and the uppipe i have on my desk is larger id than stock. i dont know exactly what that will help but some of the wrx guys are reporting good butt dyno readings with it.

i dont know what it will help if anything thats why im asking

The factory Uppipe DOES have a flex joint. It's under the heat shield.

Butt dyno's are skewed by the wallet impact, as I've found out.

It's not difficult. Try both setups and see which you like the best.

i remember the flex now. its just not my current idea of a flex.

the one on the pipe i have now is ss braided flex, kinda like a helix.

i wouldnt say that their ideas were skewed because most of us myself included got the uppipe for free. it came with the tbe which impacted the wallet at less than half the price anyone elses did, mine was a almost exactly half price comapred to anyone elses tbe and it came with these that are making my life though right now.

i could try both but then why would i be asking the question here.

My bad.

I have no idea why I thought that.......

I wouldn't expect much from the up-pipe, I think the only real gain is the cat delete on the WRX.

So I say the header.

Why do you say they'll lose heat easily because they're stainless?

What are "all" the bungs for a WRX uppipe? There should only be one, I think -- for the stock EGT sensor. I plugged that one with a drain plug from a Nissan Sentra and a 12mm copper washer.

there are 2 bungs, one for the o2 and one for the egt.

i read somewhere that stainless looses heat easily and because of that if you have stainless headers you will have uneven lag, ie if your headder is hot the lag wont be as bad but if your headder is cold than you lag will suck big time

That's weird... a stock WRX uppipe doesn't have an oxygen sensor. Is it possible that this uppipe has two EGT bungs? One for the stock sensor and one for an aftermarket sensor? The stock sensor's threads are M12x1.25, and most aftermarket sensors use pipe threads of some type.

It's kind of silly to include a bung for the stock sensor on a catless uppipe, since the purpose of the sensor is to monitor cat efficiency, but for some reason most aftermarket uppipes do have the bung.

Stainless steel is less thermally conductive than mild steel and cast iron; it should radiate less heat away. A ceramic coating will still of course improve that. The stock crosspipe and uppipe are both stainless, I believe, though they have heat shields to help further.

well the egt bung doesnt have a plug in it but the o2 one does, and i know its a o2 bung because its freakin huge compared to the egt bung. maybe its for wide band but that wouldnt make sense either.

i was told before that cast iron retains heat better than ss therefore improving performance

Hmm, yes, cast iron does retain heat better since it has more thermal mass. But it also conducts it better.

But people don't make uppipes out of cast iron, do they?

vrg3 wrote:
It's kind of silly to include a bung for the stock sensor on a catless uppipe, since the purpose of the sensor is to monitor cat efficiency, but for some reason most aftermarket uppipes do have the bung.

It's because guys on OEM engine management have to retain the sensor or the car will throw a fit and CEL.

The car will still throw a CEL if the sensor's there but there's no catalytic converter, though.

But not having it at all would be much worse wouldn't it?

I think they have a fix that guys use to trick the ecu in regards to the cat too.

so back to the orignal question......

Matt - It wouldn't be worse; it'd be the same. The fix they use is to replace the sensor with a resistor, so you don't keep the sensor around anyway.

Jason - Why not try both options? All the relevant gaskets shuold be reusable, and it's not that hard to swap these parts... Then maybe you'll be better able to decide which to keep and whether to coat it. Or are you hoping to sell one of them as brand new rather than barely used?

its more like i dont have the proper place/tools/jacks and stands/time to do it twice

i just want to do the best one and be done with it.

This should relate: Spoke with IPD's Subaru engineer and when they were testing their 425 whp Sti they ran four Egt's, one in each ex port of the stock manifold or as close as they could. Cylinder three ran @100 degrees hotter than the rest. After installing the GP Moto one-piece header, reinstalling four EGT's all exh. temps were within a few degrees of each other. This came up after asking them about why they still had stock fuel rails and the single FPR. With their high HP this will make a big difference but is why I am leaning towards the one piece headers.