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Discussion Starter #1
Redoing the exhaust system so sorry for the multiple posts regarding...


Are there any gains from running an open DP at the track?


I'm switching to a single 3" exhaust with a dynomax ultra flo muffler (dumped) and i'm considering adding a cutout to the equation for track use.

What are the advantages/disadvantages to running a cutout right after the DP?

Thanks Corral
 

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well assuming your running 3" piping and your mufflers are straight through i would assume there wouldn't be much if any gain to running open down pipe since your back pressure is going to minimal anyhow.. but that's just what i figure, i have no idea if my opinion is correct.
 

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Please elaborate on your "big increase".... just curious... I saw a 60rwhp increase, but I was getting some boost creep and I think the extra boost made most of the power... mine is a 3-1/2 into (2) 2-1/2's like yours...

I would agree. With the exhaust set up you are using, HP loss from restriction is minimal. I've noticed a big increase in power, but that's only due to the fact that I have the factory exhaust mufflers. Here's a quick video of it http://www.youtube.com/watch?v=riTdK-eZy_s
 

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Discussion Starter #7
On my setup last year - 3" downpipe to 3" y pipe to dual Dynomax Turbo mufflers (straight thru)

The car ran 10.80-10.90's thru the mufflers at 9lbs

I removed the mufflers and just ran thru the pipes dumped at axle and the car picked up 3lbs of boost and went 10.50's and picked up 3mph


I figure the cutout will make it easier for me to 'dump the muffler' if it becomes a restriction.

I'll post results as soon as i'm ready for the track - another 2 weeks or so.
 

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Discussion Starter #9
I'm very curious to see the results. I've been considering having a cutout added to my Quicktime y-pipe before it splits off.
I had the Q time Y Pipe as well but it wouldn't fit the car once I put the driveshaft loop on :curses:

That was the reason for going to a single setup.


I posted sound clips of the new setup with cutout open and closed :leghump:
 

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Please elaborate on your "big increase".... just curious... I saw a 60rwhp increase, but I was getting some boost creep and I think the extra boost made most of the power... mine is a 3-1/2 into (2) 2-1/2's like yours...
The car has never been on a dyno. I simply base my statement on the fact of racing against cars with the cut out open and closed. It seems that when I open the cut out I pull an extra car or two, depending on my traction.
 

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You will pick up a decent amount of power with a cut out of some sort. Recently on a customers car we decided to add I believe it was a 60mm Wastegate with a low spring pressure to the downpipe. It would open up at a predetermined boost level and dump right past the firewall. It picked up about 60hp and under normal driving it sounded like a completely stock car, as soon as you opened it up you could definitely tell that there was something under the hood.
 

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but you are not running any boost are you?
?? Not sure what you're trying to get at.

Is the mustang turbocharged...yes. Am I running boost...only off the wastegate spring which is 5lbs. Maybe you asked because you think it's dangerous to not tune on the dyno...i have an LM wideband so I just make sure the car runs rich to avoid detonation, and i've matched it with an MSD boost retard controller. I hope one of those answers helped with your question :king:
 
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