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TrakCord
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Discussion Starter #1 (Edited)
Bigger is Better! My 2.5" J-pipe to 3.5" exhaust build (Dub thee "2535 header")

6/28 - IT IS ALL DONE!!! System is complete! (post #76)
6/21 - J-Pipe is complete! (post #55)
6/18 - Post # 51. PICTURE of J-pipe U-bend DONE!! Rear PCD & V-band flange done


I said it and i meant it. I am on a mission to extract as much power as i possibly can out of the stock engine on stock ECU. My goal is 280whp and this is how i intend on reaching that goal. A custom 2.5" precat delete setup in a long tube design collecting right under the shift box or just after the original location of the 3rd cat into a 3.5" single exhaust running under the rear seat location and exiting just in front of the right rear tire. Is it crazy? Yes! But someones gotta try just how big can you go before it starts to hurt and that guy is me! :up::up:

Here is a screenshot of the parts necessary. I have a local exhaust shop that is going to sell me 8ft of 3.5" straight exhaust tubing for 50 buks total. Lucky for us all you need is one 90 degree bend and there is plenty of room underneath the car to make that bend and exit in front of the right rear tire.

I have a guy that is about as top quality and affordable as you can get local to me and he does TIG welding so he is going to be the chosen one to help me accomplish this. He built the exhaust on my Audi and i was super satisfied.

As always there will be plenty of dyno testing and results will come as soon as i can get this this built. I want to blow past just breaking into the 12's so mid 12's here i come!!
 

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I'm excited to see the results!

Does having the exhaust exit in front of the tire affect the tire at all? Heat it up too much/make it greasy?
 

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TrakCord
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Discussion Starter #5
I'm excited to see the results!

Does having the exhaust exit in front of the tire affect the tire at all? Heat it up too much/make it greasy?
dont know yet but considering many pro drivers plus Nascar guys have the side exit exhaust im not to concerned but i will be very sure to take tire temps and remedy as necessary. Cornering performance is the priority here not so much straight line. I am doing side exit to save weight and becuz that big of piping will hang to low going under the rear suspension.
 

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As they do in NASCAR to account for ground clearance, a rectangular tube may help keep it off the track. Probably net you at least an inch or so more of clearance.
 

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TrakCord
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Discussion Starter #8
As they do in NASCAR to account for ground clearance, a rectangular tube may help keep it off the track. Probably net you at least an inch or so more of clearance.
much appreciated but they dont use mufflers and i will be using (2) magnaflow 14161 mufflers to attempt to quiet the beast down. The mufflers will be mounted in the center of the car and right now i have the same setup just 3 inch and the mufflers are 3-4 inches off the ground.
 

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Cube doin it big! I know you hate the word, but you will be incorporating a Jpipe into your setup :) Longtube 'header' =PCD + Jpipe :D
 

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So... Did you order these parts yet?
 

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TrakCord
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Discussion Starter #11
Cube doin it big! I know you hate the word, but you will be incorporating a Jpipe into your setup :) Longtube 'header' =PCD + Jpipe :D
yup thats pretty much what i will be doing but i'd like to think of it as a longtube header just becuz i can lol

So... Did you order these parts yet?
yup that screenshot you see is the parts right before i ordered them
 

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^Lol.

Paul, I hope you make power, but I'm going to speculate a bit here :D I agree with you on the 2.5" Precats, I think you will make some power from 4K to redline. However, I think the 3.5" exhaust is a bit overkill. We won't know until after you dyno, but I'm going to say any gains that are seen will be from the 2.5" PCDs. Even if you gain power from the 3.5" exhaust, there is no way I'm doing mine over LOL. The only thing I'd consider for my exhaust is to trade for a stock exhaust plus cash and do a cutout.
 

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Ive had a larger exhaust pipe then recommended and i lost hp. I had a 3" but on a 4cyl and there is. I don't know how a v6 will act but there was a diagram that explained how too much pipe and not enough back pressure will decrease HP.
 

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Would this be for quieter daily driving, yet the ability to "open it up" when needed/wanted? What exhaust do you have now?
Exactly. I have a custom 3" with a Magnaflow resonator and Dynomax Ultraflow mufflers.

I'd love to have a 'slight' tone while cruising like the G37 (not the same tone, but same in terms of volume) and once the cutout is open, the awesome rawness. When the cutout is closed, it's like having sex with a nun for the first time. But once opened, it's like fcuking Jenna Jameson while skydiving from outer space.

NYKnick: I gained 14whp/20tq from the addition of my custom jpipe/merge collector/3" catback and UR pulley untuned. I have a feeling with a tune the gains will be much, much higher.
 

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TrakCord
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Discussion Starter #20
Ive had a larger exhaust pipe then recommended and i lost hp. I had a 3" but on a 4cyl and there is. I don't know how a v6 will act but there was a diagram that explained how too much pipe and not enough back pressure will decrease HP.
well i guess we will not know until i get all the parts in and start this process...my theory is if 3" can be put on a 4cyl and gain power why cant you go bigger on a 6cyl? There are guys that have true dual exhaust straight off the head and never merge i think with 2.25 pipes...IDK about power gains but the size is way bigger than 3.5 inches...
 
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