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Old 05-14-2003, 12:14 PM   #1
LargeOrangeFont
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Default Install pics of GP MOTO 4-2-1 equal length header

Here are some pics of the header when I got it back from the coaters, and as it was installed on the car.









Visit GP moto For more info. The install went pretty smoothly, and was very straight forward. Taking my time and taking pictures and stopping for a lunch break it took about 3 and a half hours, w\ mabye 2 and a half to 3 hours of actual work. Everything lined up very well, and the only real challenge was getting the header on all the studs\holes. You basically have to feed the up pipe portion in, and tilt the header towards the back of the car. Then you need to tilt it back foreward, and up at the same time. My only advice would be to make sure that when you thread in your up pipe studs, that you thread them in as far as possible, the shorter that they are, the easier it will be to get the header in. As you can see in the pic, the front o2 sensor is moved to right below the turbo inlet, much easier to get to. You can see in the pic that I zip tied the O2 wires to the power steering line to keep them away from the downpipe. I also plugged the EGT bung, and put a 2.2k ohm, 1\2 watt resistor in the harness. My particular system is completely catless and I added the remote rear O2 bung, and havent got a CEL yet. The downpipe is a bell mouth design, and 3 inch all the way through, and available w\ a hi flow cat that is placed just aft of the O2 bung. The catless version has a small resonator in place of a cat. The full system (header and turboback) is not very loud w\ the silencer all the way open (silencer is adjustable), and does not drone at all. The equal length header takes a lot of the"burble" out and makes the car sound smoother, more along the lines of a Porsche, I would say. Im very pleased w\ the results of the system And would highly reccomend it to any one in the market for a turboback and \or header.
The header and turbo back are the only engine mods on my car thus far, and after running the car for a couple weeks w\ just the turboback, there is a slight loss of power below 3000 rpm. The car still has far more power than it did stock to 3000, the difference is slight, but noticeable. I did have my headers thermal coated to prevent some of that lag , and to keep heat in the headers, and so far I think it is working. Power delivery seems consistent, and dosen't drop off during long stoplights . Power after 4000 rpm is AWESOME. There is no drop off in power before redline, and I would say that the car gets to redline in first almost a half a second quicker than w\ the turbo back alone. 2nd 3rd and 4th all pull almost effortlessly now. The biggest difference in the performance is from 80 to 100+ The power just dosent drop off. The small sacrifice of of off boost power, is WELL worth the topend power that this header provides. I haven't had a chance to get the car on the dyno, I will soon and let you know what it pulls.Here is a little more info about the specifics of the system.

The GP MOTO Turbo back retails for $899 and It is 3in stainless steel all the way through from bellmouth to muffler. It comes w\ an adjustable silencer, a bung in the bellmouth for a wideband O2, a flex section, and is available w\ or w\out a HI-flow cat. Soon you can have your choice of N1 canister style muffler(shown), or stock looking twin tip, for a more stealty look.

The GP MOTO 4-2-1 One piece header retails for $899 and is also polished stainless steel (I had mine thermal coated), and goes from block to turbo inlet flange. It comes w\ new gaskets and necessary hardware, and requires no modifications to install.
Ashley
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Last edited by LargeOrangeFont; 05-14-2003 at 12:54 PM.
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Old 05-14-2003, 12:46 PM   #2
mlambert
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The coating looks good on the header. I'd keep your eye on the oil filter for a few weeks, its awful close to the pipe.
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Old 05-14-2003, 01:09 PM   #3
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Thanks for the write-up and pics.

Can anyone explain the low-end loss that almost all (all?) of these aftermarket headers create? Sorry if that's a dumb question with an obvious answer. It's not obvious to me.
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Old 05-14-2003, 01:28 PM   #4
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There are basically 2 reasons for power loss, one is the material the components are made of, and the second is design.

The stock manifolds are actually pretty decent inside from a design standpoint. They are pretty smooth w\ fairly low radius bends. The reason they have more low end and less high end is pressure. Think of the stock manifold as a straw. blow through it and you can feel the pressure from the air, but if you blow really hard through the straw, you cannot get all the air through the straw. Now get a empty paper towel roll, this will represent the header. Now blow through it. You can blow till you are blue in the face and there will be very little resistance. This is the same principle that the turbo spool up works on. The stock manifold blows less air at a higher pressure, but is limited by volume. The header on the other hand can flow more air w\ less pressure, consequently, the turbo dosent spool up as fast, but has the capability to flow much more when the air speeds up.
The other point is that cast iron holds in heat better than steel tubing. The hotter the air, the quicker the exhaust gasses move. That is why I had my headers thermal coated. This keeps all the heat in the exhaust gasses, instead of transfering it off to the pipes, which then cool the gasses, which slows your turbo and robs you of power. I hope this explanation helps clear things up a little.
Ashley

Last edited by LargeOrangeFont; 05-14-2003 at 01:33 PM.
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Old 05-14-2003, 01:40 PM   #5
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Thanks Ashley, I guess I should have expounded more about what I already knew. I fully get the heat = energy, cast iron vs. stainless, coated vs. non-coated stuff. I also get exhaust speed stuff in general. I guess the missing link is that nobody every mentions how big the header tubing is. All I ever see is "Acme X-Y-1 equal/unequal header!!!" and never a mention of the inner diameter, etc.

So that explains it for me - it's pretty much just going to be a tradeoff no matter what. You're really just tuning your power to one "end" or the other (low or high) based on your header choice.

I really wish we had more dyno plots of these various headers to compare to a stock one.
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Old 05-14-2003, 02:08 PM   #6
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Well I can tell you that the borla\hks\gtspec style of header dosen't work as well and the GP moto\Invidia\whoeverelse makes one like that style. The borla\hks\gtspec style dont even give you that much more on the top end. The newer, 4-2-1 is a more advanced, better flowing design, there is far less turbulence, and much smoother transitions. A header like the GP MOTO promotes equal gas pressure from all cylinders. This is better in terms of performance, because you will get less turbulence, and better schavenging (sp) due to those same smoother bends and transitions.
The borla\hks\gt-spec style have very tight bends on the passenger side cylinders, This creates more pressure, and there is turbulence where the freer flowing drivers side cylinders, meet up w\ the slower flowing passenger side cylinders. This is why you get the burble and the somewhat lumpy sounding idle. With the header installed I think the car sounds healthier at idle, and also revs smoother\easier off idle. Unfortunately I don't have any dyno plots yet, but I will shortly. Then we can see some concrete evidence. I have all the specs as far as tubing diameter at home, I can post them later. There is a trade off, as you go w\ bigger or smaller tubing, the goal is to find the one that gives the best compromise. I'm very happy w\ the tradeoff, and I really think that after I get some ECU tuning done that the powerbandof the car will be a perfect balance.
Ashley

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Old 05-14-2003, 03:23 PM   #7
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Default no low end loss


here is a plot of the GP Moto full exhaust using a one piece header on a previously stock wrx, this means that only the exhaust has been replaced and absolutely nothing else.

regards,

del
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Old 05-15-2003, 02:18 AM   #8
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Those gains are pretty much what I was told to expect, and I will back them up w\ pulls of my own
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Old 05-15-2003, 06:05 PM   #9
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That turbo back looks like it tapers to smaller piping in several places... that doesn't seem optimal. Any comments?


-- Ed
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Old 05-15-2003, 06:46 PM   #10
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Quote:
Originally posted by Vaus
That turbo back looks like it tapers to smaller piping in several places... that doesn't seem optimal. Any comments?


-- Ed
The system is 3 inch mandrel bent all the way through. The differences you are seeing in the turbo back are the resonator in the middle of the car, which has a diameter of close to 4 inches. The picture w\ the rear O2 sensor has the flex pipe on one side, and another resonator on the other, both of these are grater than 3 inch diameter as well. The inner diameter of everything is uniform and does not fall below 3 inches anywhere in the turbo back piping.
Ashley
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Old 05-15-2003, 10:29 PM   #11
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I see... I didn't realize that was a resonator after the flex joint. Looks like a sweet turbo back on it own. Who can I look to about getting one?

thanks
-- Ed
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Old 05-15-2003, 11:28 PM   #12
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Ed-
If you'd like to know more about getting a GP MOTO turboback exhaust please PM me for more details.

Ashley
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Old 07-25-2003, 11:13 AM   #13
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bump
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Old 07-25-2003, 12:18 PM   #14
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Looks like a lot of work went into it. How much did it affect the turbo spool up? ie., at what rpm do you achieve full boost?
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Old 07-25-2003, 12:38 PM   #15
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In forth gear I achive full boost by 3000 PRM.
Ashley
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Old 07-26-2003, 12:28 AM   #16
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where are places to go for ceramic coating? would it be the same as the hi-temp ceramic stuff from a spray can that i can buy at the auto parts store?
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Old 07-26-2003, 01:02 AM   #17
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Quote:
Originally posted by Benjamin Tang
where are places to go for ceramic coating? would it be the same as the hi-temp ceramic stuff from a spray can that i can buy at the auto parts store?
Swaintech Coatings
Jet Hot coatings

I had my header JetHot2000 coated in black. They did a real nice job coating it inside and out. It is MUCH more durable than "in the can" stuff. It is almost indestructable.
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Old 07-26-2003, 11:48 AM   #18
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I got mine coated at a place local to me in so cal. Im very glad I did it. It keeps boost response the same on long trips, and greatly reduces underhood temps.
Ashley
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Old 07-26-2003, 11:28 PM   #19
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how much?
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Old 07-31-2003, 10:40 AM   #20
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I can get them coated for 200~ depending on size. On the headers I offer, I can have them coated before delivery as well
Ashley
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Old 09-18-2003, 09:48 PM   #21
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Nice headers.!
I think I have found what I am looking for now.
By the way is there any fitting problems in regards with the black plastic plash guard. Melting of plastic maybe..?

Thanks
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Old 09-18-2003, 10:42 PM   #22
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Nope it works fine (the undertray). You just have to slightly mod it. PM me I can give you more info on purschasing one!
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Old 09-18-2003, 11:23 PM   #23
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Default Re: no low end loss

Quote:
Originally posted by Deltron00
here is a plot of the GP Moto full exhaust using a one piece header on a previously stock wrx, this means that only the exhaust has been replaced and absolutely nothing else.

regards,

del
Of course there is no low end loss...you're taking out 3 cats in that dyno graph. The only true comparison would be to put that header on a car that already had a catless uppipe, and leave everything else the same...then you will see a low end loss. I would like to see a fair dyno comparison vs. the new Gruppe-S 4-1 manifold + catless uppipe. Regardless, the difference can't be that great, and I would rather pay $400 than $900 since I already have a catless uppipe.
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