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Old 09-10-2009, 11:30 PM   #1
penderperson
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Default STX/STU...what headers?

What headers are you guys using if any? Any dyno comparisons? I'm debating maddad uel vs. grimmspeed p&p.
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Old 09-10-2009, 11:57 PM   #2
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Stone Mountain Racing.
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Old 09-12-2009, 02:15 PM   #3
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grimmspeed coated p&p on our STX WRX
stock on our STU STI
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Old 09-12-2009, 02:45 PM   #4
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Quote:
Originally Posted by stimpy View Post
grimmspeed coated p&p on our STX WRX
stock on our STU STI
Were those choices cost based, performance based or something else?
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Old 09-12-2009, 04:27 PM   #5
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I have found that most headers (no matter how coated and/or wrapped they are) make more power, but suffer turbo response issues on throttle transitions. Turbo response seems to be tied to two things... Shortest path to the turbo, and exhaust heat retention. I think enough coating/wrapping can keep the heat in, but I have not seen a header that has as short a path to the turbo as the stock manifolds, especially on the passenger side.

I have also found that the STi UP is nowhere near as good as most think, and have found that I gain power and suffer no loss of response with mine.

It's PnP the OEM manifolds and iron TurboXS UP for me. All IMO, of course.
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Old 09-12-2009, 04:33 PM   #6
penderperson
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hmm...just added?!
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Old 09-12-2009, 04:37 PM   #7
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Ok, so if i'm after response(aka power under the curve), then heat and shortness are my best friend?

Do you think the smaller diameter of the maddad piece is worth the longer distance? They claim faster spool(due to uppipe diameter, but i believe their runners are a tick smaller too), with coating and wrapping and diameter considered, distance is the biggest variable, what do you think?

Edit...the TurboXS UP is discontinued, what's your next best?

How about ease of install, free from leaks, any suggestions there?

Last edited by penderperson; 09-12-2009 at 04:55 PM.
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Old 09-12-2009, 05:05 PM   #8
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Grimspeed PnP FTW! Gain response and a little power! Get it coated and with the hi-flow crossover pipe!
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Old 09-12-2009, 06:26 PM   #9
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If I re-do mine, I'd do the Grimmspeed PnP manifolds with a crossover coated and wrapped. I'd combine that with an UP that is either iron or incolnel (or otherwise as insulative as possible), preferably with an inlet matching the ported manifold and an outlet matching the turbo.
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Old 09-12-2009, 06:48 PM   #10
penderperson
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how about weight savings, not worth it for the improved response?
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Old 09-12-2009, 07:26 PM   #11
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Old 09-12-2009, 07:34 PM   #12
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Quote:
Originally Posted by penderperson View Post
Ok, so if i'm after response(aka power under the curve), then heat and shortness are my best friend?

Do you think the smaller diameter of the maddad piece is worth the longer distance? They claim faster spool(due to uppipe diameter, but i believe their runners are a tick smaller too), with coating and wrapping and diameter considered, distance is the biggest variable, what do you think?

Edit...the TurboXS UP is discontinued, what's your next best?

How about ease of install, free from leaks, any suggestions there?
the cobb up pipe is cast iron too
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Old 09-12-2009, 07:47 PM   #13
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seems like its discontinued too(not on cobb's site), but several places have it for sale??
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Old 09-12-2009, 08:46 PM   #14
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The Cobb UP is far superior to the stock STi UP. I had mine coated along with the stock manifolds and X pipe. GrimmSpeed x pipe in my future.
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Old 09-13-2009, 03:04 PM   #15
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So i was thinking(probably too hard) and I have a proposed addition to splash's theory.

Turbo response is tied to VOLUME(length and diameter) and heat retention. So when a company claims x" diameter runners, uppipe etc., it doesn't matter because that's a small amount compared to being 8" longer than stock.

Ease/practicality aside, the best header/up combo would be custom made as short as possible(or aftermarket modified) with a smallish diameter from head to turbo and ported/polished at all points for smooth laminar flow/transitions. This would only be possible with a SS or similar piece, so coating and/or wrapping would be required for the heat retention and would probably be the biggest variable. Can enough heat be retained and will this be worthwhile with benefits from length, diameter and heat?

Practicality: Maddad header has what looks like 8" extra pipe on the pax side which looks like it could be cut out. It also has smaller diameter, add a quality coating and wrapping, figure 20 less pounds on the nose and I might have the great response with light weight?
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Old 09-13-2009, 07:58 PM   #16
Splash
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To me, the path on the short side will see exhaust pulses hitting the turbine sooner than any longer path. The force at which they hit is determined by their temperature and velocity. Coating/wrapping will be required for temp control, and length and diameter matter for velocity. As I said, I would combine the shortest length with the internal diameters that match the header/manifold outlet and the turbo inlet, making the transitions as smooth as possible.

A year ago, I would have said it's better to have a smooth "ordering" of pulses, as with an equal length header, but while the EL header did make more power, even coated/wrapped, it did not have the same response on throttle transition. By the data, whether or not it was faster seemed very course dependent, obviously the longer straights involve fewer throttle changes and use the higher power more. The more technical a course was, the less the power mattered, the more the turbo response mattered.

In the long run, I chose predictability over max power as the better turbo response increases my confidence in what the car does. The data shows, when i am more comfortable, I am faster.

Also, keep in mind that this is all on a STi. The 2.5L does matter. I am not convinced ANY header design on the market today improves a 2.0L's power, but I am sure that, if it messes with my turbo response, it will most assuredly mess with a 2.0L's turbo response. If the vehicle in your profile is why you are asking, I would do a MILD PnP on the manifolds, and be particular on the UP's internal diameters matching the manifold and the turbo. The 2.0L has less exhaust volume to drive a turbo with, so you HAVE to be more careful with losing heat and using internal diameters that slow the gases down.

Again, IMO, of course.
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Old 09-13-2009, 10:07 PM   #17
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I have the Borla. Cheap, coated, really light, and proven to make power. There was a header dyno comparison done back in the day, I think by downshift1, can't find it right now though.
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Old 09-14-2009, 09:53 PM   #18
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Old 09-14-2009, 11:59 PM   #19
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This is the one I was thinking of:
http://forums.nasioc.com/forums/show...ghlight=header

Results here:
http://forums.nasioc.com/forums/show...&postcount=725

The graphs are hard to read but you get the idea.
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