Best aftermarket exhaust?

  1. VooDuuChild

    VooDuuChild Senior Member

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    At least on the Si, from what I have read, the stock exhaust flows totally well until you hit about 280 hp, and then it starts to restrict. So at least on the Si, any change will be to sound...and depending on the flow characteristics, removing any part of it, could in theory drop power....but stock, you ain't gaining nothing but sound...on the Si until above 280 hp. I believe those numbers came about during PRLs testing, I think on their white Si. I am pretty sure that's where I read it...if wrong, sorry lol. Could have been testing from any one of the vendors here doing some mad R&D....kudos to them all...
     
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  2. Cdw1008

    Cdw1008 Member

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    I’ve just replaced my mufflers with resonators and it’s not a bad compromise between stock and a big $$ aftermarket exhaust system.
     
  3. fabster22

    fabster22 Senior Member

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  4. LilToTo17

    LilToTo17 Senior Member

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  5. JC671

    JC671 Youtube: JaySi.671

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    Here’s my question....

    If there a difference or drop off in power when you have a full 3inch downpipe/front pipe and say your catback is smaller say 2.75 or 2.5?

    Would a straight 3 inch from the turbo back be best?

    The 3 inch catback currently aviable seem to have issues. MAP is having some quality/alignment issues with the tips not lining up.

    I’m looking for burnt tips exhaust but the other in the 3 inch category ain’t my style of tip or sound.

    Can someone testify.... oh course in running a full three inch from the turbo back, I plan to build bigger I’m the future with turbo and all and would hate to have to buy another exhaust is the exhaust pipikgnsize was limiting the performance gains.

    I’m looking for a loud exhaust too with something that’s not so quiet. No emissions testing where I’m at so I’ll be completely catless with fromtnpipe and downpipe.


    Can someone shed some light on this. Thanks...
     
  6. 10GenPearlSi

    10GenPearlSi Old Man

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    Hot air expands and cold air shrinks. That is the same way with exhaust gases. That means that the exhaust gasses take a large diameter pipe to flow easier when it is hot after just being burnt. It cools down fast and by the time it gets to the exhaust pipe it flows easily in a smaller pipe. That is why they say that you don't make any more power by removing the stock exhaust system even though it is only 2.5 inches.
     
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  7. LilToTo17

    LilToTo17 Senior Member

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    Stock is actually 2.25”
     
  8. 10GenPearlSi

    10GenPearlSi Old Man

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    Still not a problem. I think PRL ran a Civic with only a downpipe and no exhaust system and did find any increase in power. They decided it wasn't worth it for them to offer an aftermarket exhaust system.
     
  9. LilToTo17

    LilToTo17 Senior Member

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    Well I have never seen them make an exhaust system regardless for past generation Hondas or Subies
     
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  10. 10GenPearlSi

    10GenPearlSi Old Man

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    Good point!
     
  11. LilToTo17

    LilToTo17 Senior Member

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    But yes there are no restrictions at all from the exhaust part since even Eman who’s running the oem type r exhaust which I believe is 2.5” has no restrictions at 465whp
     
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  12. James3spearchucker

    James3spearchucker Senior Member

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    First let's be clear: PRL does NOT make exhaust systems and therefore does not test exhaust systems. As such, you will never get any data from them regarding decent cat-back exhaust systems. Also, if you use common sense, anyone in the business to make money will probably push what products THEY HAVE that make more power. If you did everything you could do to make power with an unlimited budget you could probably push this 1.5 to 1000 horsepower but alas...what millionaire would do that?

    Now that that's out of the way....1.5T Civics come in three flavors from the factory. Mine is the Sport Hatchback. I designed and built my system and used advice and parts from Italian exhaust shop Supersprint. They are great in every possible way. What I got regarding diameters(which are measured on exterior of pipe) is that you do need to know how much HP you want to push. If you want unlimited potential up to 375-400HP 3" is recommended. If you want up to about 330 HP 2.75" will do fine. Having cut and tig-welded my system from stainless pipes from an SI (which have 60mm from factory) I learned the hard way how hard it is to build your own system and get all the hangars to line up and your elevations just right. That said, wit no other mods, the engine breaths better at all RPM's from idle and the better flow is especially noticeable above 3000 RPM and the engine pulls to redline unlike before when it would go to redline but begrudgingly.

    3" exhaust will sound deeper than 2.5" but the flow(and torque) may be somewhat reduced somewhat just like if you decat the downpipe you will lose torque but gain horsepower up too. As far as the step you mentioned from the 3" downpipe/front pipe to 2.5", first remember that ideally you want to go from smaller to larger exhaust as you go back because cooling exhaust is slower and it helps your scavenging and to accelerate the exhaust exit as pressures equalize at the exhaust tips. If I had a 3" in front I would stay at 3" throughout. But depending on other factors you may want the sound or clearance of the 2.5 and in that case you can buy a 2.5 and use a 3" to 2.5" reducer to install in between them. It's fairly easy mod so there is not an abrupt step there.
     
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  13. James3spearchucker

    James3spearchucker Senior Member

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    This is my exhaust, using 60mm pipe from SI, a 70mm resonator in the middle and 60mm muffler in rear. It flows great but I kind of wish the tone was a little deeper. The cat and front pipe are still stock. I still can mod it a little via tune and slightly larger turbo but I couldn't run a big turbo well.

    IMG_4993.JPG

    IMG_4994.JPG
     
  14. LilToTo17

    LilToTo17 Senior Member

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    PRL tested with and workout the exhaust and no gains or differences on dyno
     
  15. James3spearchucker

    James3spearchucker Senior Member

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    So what is your point and the relevance?
     
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