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Open down pipe ls1? Gains?

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Old May 26, 2016 | 11:04 AM
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Default Open down pipe ls1? Gains?

Hey guys, I've got a 2000 SS with a turbonetics t76. It is making 450-500rwhp, and is running through a single 3 inch exhaust with no muffler. From looking at everyone else's builds, I feel like it's being choked a bit. I read another guy on here picked up 60whp at 10psi just by removing his exhaust system. I have had issues with leaks, and from areas hanging too low, and I wouldn't mind running an open down pipe. What would you guys reccomend?
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Old May 26, 2016 | 12:26 PM
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Is it just 3" out the turbo and straight pipe to the rear?
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Old May 26, 2016 | 01:47 PM
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It's really going to depend on the setup. But in general, almost every turbo setup hates backpressure downstream of the turbo. But to put it in perspective and give you an example.... many moons ago when I had the APS twin turbo setup on my car, I had the car on 7psi, and it had ORY, and 3" magnaflow catback. I wouldn't even consider the exhaust that restrictive in the first place. But I also had a cutout at the end of the "I" pipe. So when my tuner tuned it all up for me, we decided to do a test.... dyno results back to back with the cutout open vs the cutout closed. The results were just flat out unbelievable. Here they are:

Cutout Open: 571whp
Cutout Closed: 501whp

I couldn't believe it. My car lost 70whp with just the cutout change. I couldn't imagine if I didnt have the cutout, and here I would be thinking 501 was the most this setup had in it, not even knowing I was leaving 70whp on the table.

Good luck.
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Old May 26, 2016 | 01:54 PM
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Originally Posted by svslow
Is it just 3" out the turbo and straight pipe to the rear?
Yes, 3" down pipe
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Old May 26, 2016 | 01:59 PM
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Originally Posted by 93camaro_zzz
It's really going to depend on the setup. But in general, almost every turbo setup hates backpressure downstream of the turbo. But to put it in perspective and give you an example.... many moons ago when I had the APS twin turbo setup on my car, I had the car on 7psi, and it had ORY, and 3" magnaflow catback. I wouldn't even consider the exhaust that restrictive in the first place. But I also had a cutout at the end of the "I" pipe. So when my tuner tuned it all up for me, we decided to do a test.... dyno results back to back with the cutout open vs the cutout closed. The results were just flat out unbelievable. Here they are:

Cutout Open: 571whp
Cutout Closed: 501whp

I couldn't believe it. My car lost 70whp with just the cutout change. I couldn't imagine if I didnt have the cutout, and here I would be thinking 501 was the most this setup had in it, not even knowing I was leaving 70whp on the table.

Good luck.
Wow! That is crazy! Thank you very very much for the response
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Old May 26, 2016 | 06:10 PM
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Originally Posted by 93camaro_zzz
It's really going to depend on the setup. But in general, almost every turbo setup hates backpressure downstream of the turbo. But to put it in perspective and give you an example.... many moons ago when I had the APS twin turbo setup on my car, I had the car on 7psi, and it had ORY, and 3" magnaflow catback. I wouldn't even consider the exhaust that restrictive in the first place. But I also had a cutout at the end of the "I" pipe. So when my tuner tuned it all up for me, we decided to do a test.... dyno results back to back with the cutout open vs the cutout closed. The results were just flat out unbelievable. Here they are:

Cutout Open: 571whp
Cutout Closed: 501whp

I couldn't believe it. My car lost 70whp with just the cutout change. I couldn't imagine if I didnt have the cutout, and here I would be thinking 501 was the most this setup had in it, not even knowing I was leaving 70whp on the table.

Good luck.
So for most part the cat was the restriction, not the actual exhaust system
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Old May 26, 2016 | 07:07 PM
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Off road y

No cats...
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Old May 26, 2016 | 07:13 PM
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Ahh right, when he said cat-back assumed he meant it.

Definitely a surprising difference
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