APEX'i N1 exhaust + downpipe with 3'' output diameter. Which frontpipe ?

[Se-BASS-tian]

Hi everyone, I'll soon be ordering a complete exhaust (HJS downpipe + frontpipe (I haven't decided which one) + APEX'i N1 exhaust).

Until now, I've decided to go with the APEX'i exhaust and the dedicated APEX'i frontpipe (which has a diameter of 2.75" / 70mm).

However, the downpipe I want to use (HJS - part number 90 81 6000) has a 3" / 76mm outlet.

Would it be a good idea to go with a frontpipe that seems to be an additional restriction (3" downpipe -> 2.75" frontpipe -> 3" exhaust) ? I'm considering an alternative, an RV6 or PRL frontpipe, which has a 3" / 76mm diameter.

Why do APEX or Spoon use a smaller diameter frontpipe? Were their front pipes sized for the OEM downpipe, which appears to have a smaller diameter, and would a 2.75" diameter make sense as a result of increasing the diameter on each subsequent component?

For exhaust backpressure, wouldn't it be better for these diameters to be relatively large?

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HJS downpipe vs OEM downpipe (photo from kep-shop.de shop):

 

[apl360]

Ideally you’d want to remain 3” from the dp back

but comparing to stock, anything’s better than stock

you are going to create a louder sounding idle tho. It won’t actually be louder in terms of decibel gain. It’s just the tone changing some. You’re also going to lose some texture in your sound when driving.

 

[getRIGHT]

I’m using the APEX’i N1 exhaust with a RV6 front pipe

 

[rondre3000]

Ideally, yes, the best situation would be a full 3" path from your turbo to the exhaust.

Will using a 2.75" front pipe instead of a 3" significantly impact your performance? No. Unless you're chasing 400+ #'s I doubt you'd even notice via the butt dyno on the street.

I went MXP for my front pipe because I was able to get it quickly and cheap (I believe sub $300 vs $400 for RV6/PRL and $500+ for the Apexi).

 

[TypeRVA]

People make 500hp on the stock exhaust. It's not a huge restriction in the cars.

 

[AspecR]

Hi everyone, I'll soon be ordering a complete exhaust (HJS downpipe + frontpipe (I haven't decided which one) + APEX'i N1 exhaust).

Until now, I've decided to go with the APEX'i exhaust and the dedicated APEX'i frontpipe (which has a diameter of 2.75" / 70mm).

However, the downpipe I want to use (HJS - part number 90 81 6000) has a 3" / 76mm outlet.

Would it be a good idea to go with a frontpipe that seems to be an additional restriction (3" downpipe -> 2.75" frontpipe -> 3" exhaust) ? I'm considering an alternative, an RV6 or PRL frontpipe, which has a 3" / 76mm diameter.

Why do APEX or Spoon use a smaller diameter frontpipe? Were their front pipes sized for the OEM downpipe, which appears to have a smaller diameter, and would a 2.75" diameter make sense as a result of increasing the diameter on each subsequent component?

For exhaust backpressure, wouldn't it be better for these diameters to be relatively large?

-------------------

HJS downpipe vs OEM downpipe (photo from kep-shop.de shop):

From a purely performance standpoint yes it would be better for a larger diameter. The JDM brands have noise regulations they have to meet so they tend to not go with the largest possible diameter to help keep the noise in check.

Like TypeRVA said the stock exhaust is good for over 500whp, the difference in power between a 2.75 inch front pipe and a 3 inch is relatively insignificant unless you absolutely have to make all available power.

 

[Mawfuqqa]

People make 500hp on the stock exhaust. It's not a huge restriction in the cars.

I was surprised by this when searching about hence decided to just fuck about with the stock pipes.

To op: Ideologically and if for peace of mind you'd want same diameter all the way or step up with a cone or megaphone transition. ie.) 2.5" to cone/megaphone transition to a 3" back

 

[TypeRVA]

I honestly just want a de5 exhaust modified to fit

I was surprised by this when searching about hence decided to just fuck about with the stock pipes.

To op: Ideologically and if for peace of mind you'd want same diameter all the way or step up with a cone or megaphone transition. ie.) 2.5" to cone/megaphone transition to a 3" back

 

[apl360]

I honestly just want a de5 exhaust modified to fit

I gave away my stock de5 exhaust to this young man with a fl5. It didn’t fit. It’s about 4” too long

I haven’t spoke to em in a while but iirc he was gonna take it to an exhaust shop so they can mod it to fit.

 

[TypeRVA]

I think it's all at the tips due to the different rear bumper.

 

[Clark_Kent]

@JDM_DOHC_SiR installed a DE5 exhaust on his FL5 some time ago.

https://www.civicxi.com/forum/threads/integra-type-s-exhaust-swappable.52758/post-876135

 

[apl360]

I think it's all at the tips due to the different rear bumper.

Could be. I can’t recall

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