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Old 08-17-2020, 04:56 PM   #1
kgozi
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Default JDM twinscroll downpipe, restrictive design a dealbreaker?

One of the last bits of my build is the exhaust, is this restriction going to really hinder performance on the dyno when I get a pro-tune?
If so I will have to get it cut and reweld from a shop. Has anyone stayed with this design?
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Old 08-17-2020, 05:20 PM   #2
Psychoreo
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Originally Posted by kgozi View Post
One of the last bits of my build is the exhaust, is this restriction going to really hinder performance on the dyno when I get a pro-tune?
If so I will have to get it cut and reweld from a shop. Has anyone stayed with this design?
I ran the stock JDM twinscroll downpipe on a Ver8. Stock everything and made ~280whp/272wtq. That might be backwards, it might've been 272whp/280wtq. Either way, that's about what it made with the stock turbo/downpipe and an e-tune on the dyno.

Are you swapping to some big glorious twinscroll turbo, or running the stock one?

What engine?
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Old 08-17-2020, 09:46 PM   #3
kgozi
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Originally Posted by Psychoreo View Post
I ran the stock JDM twinscroll downpipe on a Ver8. Stock everything and made ~280whp/272wtq. That might be backwards, it might've been 272whp/280wtq. Either way, that's about what it made with the stock turbo/downpipe and an e-tune on the dyno.
Are you swapping to some big glorious twinscroll turbo, or running the stock one?

What engine?
Version 8 EJ207 stock turbo basically a “stage 2” buIld
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Old 08-17-2020, 11:42 PM   #4
Psychoreo
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You'll be fine.
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Old 08-18-2020, 09:04 PM   #5
kgozi
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You'll be fine.

Does your jdm downpipe have the same design where it gets more restrictive like mine? Not sure if this is a common design for all of them
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Old 08-18-2020, 09:31 PM   #6
Psychoreo
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Does your jdm downpipe have the same design where it gets more restrictive like mine? Not sure if this is a common design for all of them
I honestly don't remember. I did the swap ~8 years ago. If you're really worried about it, when you bring the car in for exhaust work to have the DP lengthened (I'm assuming that's a JDM length DP), have the shop match the larger size. It's not going to make a noticable difference, but you'll feel better.
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Old 08-20-2020, 01:33 AM   #7
D-Rodman
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You may give up 5whp with the factory donut gasket taper.
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