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Old 04-07-2009, 02:04 AM   #1
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was thinking the other day that the most restrictive part of the exhaust besides the fron manifold is the cross over into ream manifold. has anyone done a custom exhaust where you put in a front plog cut the cross over and route it down to y into the main exhaust. then cap the inlet on the rear mainfold and run a line down from it (removing the cat) and y in the front pipe. this would not decrease exhaust velocity improve flow and be fairly inexpensive. anyone tried it or have thoughts? i know pacesetters are out ther for 400btw but just wondering. my 3.8 is na by the way i have a cai and a intense pcm as well as the 180 stat.
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Old 04-07-2009, 02:10 AM   #2
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BADBUICK;

Please add your year and trim of your vehicle to your signature line. That way when you start asking questions in other areas of the forum, we all have a better idea on how to assist you. Click on "Quick Links" above, go down to "User Control Panel" and then click on "Edit your Signature" It'* pretty straight forward from there.

I don't recall anyone doing what you suggest. However; I think the reasoning in decreasing exhaust system back pressure is to allow the system to handle whats being throw at it. So, if you increase the pipe size from the collector, go with a hi-flo cat and less restrictive mufflers you accomplish the same thing.

I think what you are suggesting is that the exhaust pressure will be the same, but you are just adding it into the system at different areas.
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Old 04-07-2009, 07:44 AM   #3
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Having the CAI helps and opening the exhaust a little well help, unless you run too big of a pipe, but you still have some blockage in the intake manifolds, I forget how much a ported UIM is but not cheap IIRC
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Old 04-07-2009, 12:08 PM   #4
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Quote:
Originally Posted by Purplehazeir View Post
BADBUICK;

Please add your year and trim of your vehicle to your signature line. That way when you start asking questions in other areas of the forum, we all have a better idea on how to assist you. Click on "Quick Links" above, go down to "User Control Panel" and then click on "Edit your Signature" It'* pretty straight forward from there.

I don't recall anyone doing what you suggest. However; I think the reasoning in decreasing exhaust system back pressure is to allow the system to handle whats being throw at it. So, if you increase the pipe size from the collector, go with a hi-flo cat and less restrictive mufflers you accomplish the same thing.

I think what you are suggesting is that the exhaust pressure will be the same, but you are just adding it into the system at different areas.
I would be removing the cat and already have a low restriction muffler. im thinking i would go from 3inches from right out of the colector till the front pipe joins then drop tp 2.5 to keep velocity high. I could be wrong but my thinking on the pressure is P= F*A so with a custom y rejoining the pipes the area of rejoin would be over 3-6 inches instead of at a t. ill post some crude paint photos i know words and ideas dont always match up lol. My question is why is this the only car that suffers from removing the cat and putting in a "racepipe" never heard of another car struggle with that.
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Old 04-07-2009, 12:15 PM   #5
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Sounds like a nice idea, but I don't see any advantage to doing that. I'm running 14 pounds of boost and still use a cross over pipe that connects at the rear header and then threw a 3" cat and 2.5" exhaust. No problems here.
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Old 04-07-2009, 12:25 PM   #6
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this is what i was thinking where the red would be the mods
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Old 04-07-2009, 12:27 PM   #7
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Quote:
Sounds like a nice idea, but I don't see any advantage to doing that. I'm running 14 pounds of boost and still use a cross over pipe that connects at the rear header and then threw a 3" cat and 2.5" exhaust. No problems here.
But then why do people use headers im sure that works fine but is it possible to work better. in my head it just seems like for the price of a front plog and some bent pipes i could make a much better flowing system.
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Old 04-07-2009, 12:34 PM   #8
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If you want to improve your flow, a Plog on the front and a new down pipe is teh way to go. Your downpipe is a real problem. Also space is a problem. Things get tight behind the engine. Take it from someone that'* done a fair amount of exhaust work. How ever, if you are set on doing this, I would love to see pictures of the work. Would be nice to see.
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Old 04-07-2009, 06:38 PM   #9
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I wouldnt say im set on this just from looking at it it doesnt seem that hard i have a welder and all that fun stuff but in your opinion just the plog and downpipe would get the smae or better results?
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Old 04-07-2009, 06:43 PM   #10
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Ya, you will be suprised at how restrictive the stock downpipe is. There'* another pipe inside that one.
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