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Discussion Starter #1
I'm stuck on my build. I've always read and heard that shorter, bigger, freerer flowing exhaust makes the most power on a boosted setup, but I was wondering how much of a difference would there be in say a 3" dp with a turn down past the oil pan or a nasty drag car hood exit?
I would rather the dp just so it doesn't draw so much attention when on the street, but if it would free up maybe 20-30whp I'll deal with it for the sake of being faster lol
It's a forged, e85 z6, 400whp atleast and 20+psi. I just wanted you guys thoughts on it and if it will make a difference for me.
 

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I was on the same boat not to long ago. Hood exit will limit the drive-ability but will help spool the turbo a little bit sooner. I had my wastegate pipe out the hood last year and it was a pain that it gets me worried if its going to rain or not.

If you don't want to draw a lot of attention you can flip it towards the bottom and release it there, then you don't have to worry about water going in.

Here's what i did to mine
3" open to the side



Hope it helps.
 

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I don't think the difference would be as big as 20whp between hood exit or downpipe past the oil pan.

My current build has a valve that opens under boost, opening up a 3" open downpipe straight down from the turbo, about same length as hood exit. Under cruise the valve is closed and it goes out a 2" stock looking exhaust. :D

EDIT: Pic

 

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And I agree I would go bumper dumper or fender dumper before hood exit, so that water isn't a concern.
 

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Discussion Starter #5
I don't think the difference would be as big as 20whp between hood exit or downpipe past the oil pan.

My current build has a valve that opens under boost, opening up a 3" open downpipe straight down from the turbo, about same length as hood exit. Under cruise the valve is closed and it goes out a 2" stock looking exhaust. :D

EDIT: Pic

That's gangster lol did you make that yourself? I love the way looks

@jvtec I thought about a bumper dumper but figured they would be a pain to route. Is their pics in your build thread of how its ran?

Thanks for the pics too guys
 

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Discussion Starter #9
+1 on bumper/wheel well exit. I'd go passenger side unless you want everyone to see the fireworks :)
I just don't like how close the dp and the intercooler piping are, seems like it would get hot. I'll probably just go with the turn down because it's easier and won't shoot flames outside the car lol
Those boost controlled valves are really neat, I wish they weren't so much.
 

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Remember that if you do dump down and out straight out to the oil pan it will resonate the whole cabin. Thats the problem im having right now usually not too bad I get used to it but sucks on the freeway and for daily driver. I really think that if I did a bumper exit still open downpipe you wont lose the power and im willling to bet it would be MUCH quieter.
 

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With a completely free-flowing mandrel-bent 3-4" exhaust, how many ponies could you really be losing with a typical rear-bumper exit exhaust vs DP exit exhaust setup? I wish I had the time to see the dyno differences for myself on my setup, but 400whp is EASILY doable with a "normal" free-flowing rear exiting exhaust setup...even with a muffler!
 

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Run the 3" exhaust if you're going to daily it.
 

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I have 3" mandrel straight to the back but i have an electric cutout about a couple feet back from the pan. seems to work out pretty well, is ok noise wise then when i wanna have fun just open it up. Kinda tight to the ground with a low car, i ripped my old cutout off on the ground. But if thats something your looking for i love mine. I would like to change it to something like above, either electric with switch or boost activated but off the dp to the front bumper, Just not sure how id do it.
 

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I have 3" mandrel straight to the back but i have an electric cutout about a couple feet back from the pan. seems to work out pretty well, is ok noise wise then when i wanna have fun just open it up. Kinda tight to the ground with a low car, i ripped my old cutout off on the ground. But if thats something your looking for i love mine. I would like to change it to something like above, either electric with switch or boost activated but off the dp to the front bumper, Just not sure how id do it.
I thought about E cut-out as well, but most of the people here have bad luck with it getting stuck and so I skipped it. Glad it worked good for you though
 

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Ive also heard the E-cutouts stick but I dont believe their is any HP difference between say 3'' to the back open downpipe or 3'' bumper exit ODP???
 

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^^ That does look cool
 

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HTML:
BADDD ASSSSSSS :rockon:

wanna write/have you written a DIY on this?
Should be enough pics in my build thread if you wanna copy it.

Fairly straightforward. Build the valve first, then attach the wastegate. I put an adjustable spring on mine as well.

I made mine all from scrap metal.
 

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Should be enough pics in my build thread if you wanna copy it.

Fairly straightforward. Build the valve first, then attach the wastegate. I put an adjustable spring on mine as well.

I made mine all from scrap metal.
Is it actually machined for a seal? Its hard to tell in the pictures
 
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