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I am thinking about purchasing the alpha series header for my 2 door 2015 civic si . I was wondering what exhaust system you guys recommend. And if u know any links here for install .thanx .
 

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Personally 3inch is overkill for N/A unless you like noise. 3inch no cat, and skunk 2 exhaust for over the top loud.
I've got full race exhaust and it sounds good, but turbo tend to help reduce noise some. I've meet a N/A Civic Si owner that told me his full race exhaust he didn't like because it was too quite...so take that for what it's worth.
Before turbo I had a RV6 catted down pipe on stock exhaust, and I loved it. I could hear the engine, but it was far from loud or annoying. The RV6 didn't need motor mounts to keep it from banging on the firewall, and I highly doubt theres power to be gained by going to 3".

You may like loud, either way you may want to put your goals (power+quite/power+loud/future turbo/supercharging/nitrous).
 

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Theres a few youtube videos on how to install a downpipe. The process is the same for all of them so just find a video that best helps you. Im running full race catted downpipe and full race exhaust and i love it. Catless is going to be much louder and produce a lot more drone and rasp. If thats aomething that doeant bother you then go for whatever setup you want. Go on youtube and just search different setups and see what you like.
 

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I've meet a N/A Civic Si owner that told me his full race exhaust he didn't like because it was too quite
That dude must be going deaf because it's not even remotely close to quite. And I have RV6+Full race exhaust.
 

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I've meet a N/A Civic Si owner that told me his full race exhaust he didn't like because it was too quite
That dude must be going deaf because it's not even remotely close to quite. And I have RV6+Full race exhaust.
He was a young guy, he came from a 8th gen with skunk2 exhaust, didn't say any other mods. I thought he was crazy too but chalked it up to maybe "louder=faster". I know a turbo makes it quieter, but who knows how much. If I catch him out again I'll inquire about this, and maybe make a video off of both cars.
 

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He was a young guy, he came from a 8th gen with skunk2 exhaust, didn't say any other mods. I thought he was crazy too but chalked it up to maybe "louder=faster". I know a turbo makes it quieter, but who knows how much. If I catch him out again I'll inquire about this, and maybe make a video off of both cars.
As you soon as you said Skunk2, it makes a whole lot of sense now. Probably had the N1 and thing is stupid loud. If I had like a GoPro, I'd make a video of the FR+RV6.
 
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Any significant hp gains would require a lot of money, sacrifice engine life and durability and for little benefit. You're dealing with an economy car engine.
 

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Any significant hp gains would require a lot of money, sacrifice engine life and durability and for little benefit. You're dealing with an economy car engine.
Tell a civic owner it's not ideal to mod their car ?.
 

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Any significant hp gains would require a lot of money, sacrifice engine life and durability and for little benefit. You're dealing with an economy car engine.
Don't come in here with your logic and sense! Get outta here!
 

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I am thinking about purchasing the alpha series header for my 2 door 2015 civic si . I was wondering what exhaust system you guys recommend. And if u know any links here for install .thanx .
Check my IG I have or can send you sound clips of a RV6 catless downpipe paired with Invidia Q300. IMO sounds the best... maybe go catted if you want less rasp.
 

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I listened to VitViper prior to his departure and got a 3" downpipe as that was his recommendation for NA or compressed. I was going to supercharge so I went catless, but didn't and wish I'd have sacrificed a few ponies and got the high-flow cat instead. Skunk 2, Full Race, I don't think you can go wrong with any quality product.

I have the 3" Full Race catless downpipe and 3" exhaust on our 2015 Si. It has a wonderful, defined voice, but is not loud at all. Not quiet, but certainly not loud. A little louder inside the car than I'd find ideal, but not outside to the world. I love it.

Highway cruising speeds are over the low rpm drone range (1000-2000 rpm). We've made many a 700 mile road trip and it's totally doable.

With Vit's tune, the low-end is about like stock, far more usable mid-range torque than stock and 20-25 extra ponies on top, depending on the Dyno run. Very decent milage, too, considering the high rpm the K24 spins at.

How this helps and best of luck to you!

P.S. I've entered the dark zone; just picked up my 2019 CTR. Delicious!
 

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Invida Q300 and either Junk2 Alpha, or Invida Header FTW. Or maybe a Vibrant header if you can find one. The Invida products of course will bolt right up to each other.
 

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I have alpha headers on my CRX straight 3" to vibrant exhaust. Very punchy but my build is a 14:1 e85 k20/24 Type S (6spd;LSD); Twin Disc Stage 4 Completion Clutch. I agree that is loud but for my NA it does what it's supposed to do.
Good-night I bet that car is a blast. I request YouTube links now.
 
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