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I have been looking for some opinions on a new exhaust with header and wanted to know what makes more power on a custom header with megaphone..

A cut out at the end of the header, which is like open header.

OR

A full 3" exhaust straight back.

?????
 

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RoLlInG sToNeD
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First of all running open header is not good to run for our car. If you run an open header it fucks with the 02 sensors and makes the car dump loads of fuel in when you engage vtec. Im not sure if it's that exact reason but i know for a fact it is not good to do. My buddy is a certified tech at the acura dealer and he told me something like that cause I asked him. haha As for the 3" exhaust I think that might make your car sound very loud and lose some power. I think your only supposed to run 3" piping if your turbo but not positive.
 

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First of all running open header is not good to run for our car. If you run an open header it fucks with the 02 sensors and makes the car dump loads of fuel in when you engage vtec. Im not sure if it's that exact reason but i know for a fact it is not good to do. My buddy is a certified tech at the acura dealer and he told me something like that cause I asked him. haha As for the 3" exhaust I think that might make your car sound very loud and lose some power. I think your only supposed to run 3" piping if your turbo but not positive.
It would be on a tuned set up.. 3" Dont lose power... In fact u gain with it. There is a thread on here about it.
 

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First of all running open header is not good to run for our car. If you run an open header it fucks with the 02 sensors and makes the car dump loads of fuel in when you engage vtec. Im not sure if it's that exact reason but i know for a fact it is not good to do. My buddy is a certified tech at the acura dealer and he told me something like that cause I asked him. haha As for the 3" exhaust I think that might make your car sound very loud and lose some power. I think your only supposed to run 3" piping if your turbo but not positive.
so I've heard since after the turbo you dont need more backpressure so the freer flowing the better

It would be on a tuned set up.. 3" Dont lose power... In fact u gain with it. There is a thread on here about it.
I think it may lose torque, and that is a precious thing for us. All you really need is a 2.56", 2.75" at the most depending on your RH. I think the DC RH ends at 2.75" so perhaps an exhaust with piping diameter that matches will work out well. However I doubt that you will see more power if you go bigger than that.

If I'm wrong please correct me.
 

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Discussion Starter #5
so I've heard since after the turbo you dont need more backpressure so the freer flowing the better



I think it may lose torque, and that is a precious thing for us. All you really need is a 2.56", 2.75" at the most depending on your RH. I think the DC RH ends at 2.75" so perhaps an exhaust with piping diameter that matches will work out well. However I doubt that you will see more power if you go bigger than that.

If I'm wrong please correct me.
DC is actually one of the worst headers to buy.. I think they end at a 2.25. The 3" will lose minimal torque but will gain. There is a thread on here with a dyno comparing both, check it out.
 

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Well if this is a street car, then perhaps you can make a split compromise. Build a ''quiet'' 3 inch exhaust using a burns "26 stainless muffler or magnaflow 18'' round muffler as a resonator, us a WS2 universal muffler or go with any number of Magnaflow, or Dynomax super turbo muffler. Remember different length rear mufflers from either manufacturer will affect sound as obviously will your resonator choice. You can create a very reasonable sounding 3 inch exhaust that is streetable. In combination with your exhaust you could utilize a electronic exhaust cutout that you could open/close from within the car. I'd imagine you would also have a separate dyno tune for open exhaust cutout vs. 3 inch cat back. Just upload your e-cutout .kal for racing or whatever it is you do.
 
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How much power is this motor expected to make? If we are talking about a sub-250hp motor, a 65mm exhaust is plenty. 3" exhausts are overkill and a waste of money on most N-A cars.
 

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It would be on a tuned set up.. 3" Dont lose power... In fact u gain with it. There is a thread on here about it.
you do loose power on a 3" in the low and mid range when you dont have the supporting mods, and the little bit of top end you gain is not worth it.


3" is for turbos and aggressive N/A motors
 

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you do loose power on a 3" in the low and mid range when you dont have the supporting mods, and the little bit of top end you gain is not worth it.


3" is for turbos and aggressive N/A motors
exactly. daily driven cars should opt for more midrange/lowend. youll need it more so then 5k rpms and up.
 

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I dd my setup I have a 3 inch it sounds nice on the low rpms
 

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AWD FTW
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yah me. I should make a vid. ASP 3inch piping to burns 3in muffler.
 

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Engineering
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i'd much rather go with a 2.5" turndown right after the megaphone. run a burns muffler, some tubing, then a turndown tip. depending on how much space you have.
 
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First of all running open header is not good to run for our car. If you run an open header it fucks with the 02 sensors and makes the car dump loads of fuel in when you engage vtec. Im not sure if it's that exact reason but i know for a fact it is not good to do. My buddy is a certified tech at the acura dealer and he told me something like that cause I asked him. haha As for the 3" exhaust I think that might make your car sound very loud and lose some power. I think your only supposed to run 3" piping if your turbo but not positive.
This isnt true, people do it all the time with all types of cars.

so I've heard since after the turbo you dont need more backpressure so the freer flowing the better



I think it may lose torque, and that is a precious thing for us. All you really need is a 2.56", 2.75" at the most depending on your RH. I think the DC RH ends at 2.75" so perhaps an exhaust with piping diameter that matches will work out well. However I doubt that you will see more power if you go bigger than that.

If I'm wrong please correct me.
How much power is this motor expected to make? If we are talking about a sub-250hp motor, a 65mm exhaust is plenty. 3" exhausts are overkill and a waste of money on most N-A cars.
you do loose power on a 3" in the low and mid range when you dont have the supporting mods, and the little bit of top end you gain is not worth it.


3" is for turbos and aggressive N/A motors
None of the above bold, is true.

Here is a dyno from another member, who btw is a tuner.
http://forums.clubrsx.com/showpost.php?p=19553135&postcount=1

It also says on Evans Tuning site that 3" is the best exhaust to run on an all-motor k-series.
 

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AWD FTW
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Nice any pics of the exhaust??? Which muffler did you go with?
i might take some tom. went with the 17 inch long with a turn down like the toda exhaust.

since im on stock suspension again, i had to have my 3in back.
 

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i might take some tom. went with the 17 inch long with a turn down like the toda exhaust.

since im on stock suspension again, i had to have my 3in back.
Nice.... Is it loud? Did u use a resonator as well?
 
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Here is a dyno from another member, who btw is a tuner.
http://forums.clubrsx.com/showpost.php?p=19553135&postcount=1

It also says on Evans Tuning site that 3" is the best exhaust to run on an all-motor k-series.
You should ask Drob about the 2.5" ID resonator he still had in the car for that dyno test with his "3-inch system". I would make sure to get your facts straight before you go parroting flawed data as gospel. I will stick to my statement that anything over 65mm is a waste of money on an RSX with simple bolt ons. I am not telling anyone what to or what not to install on their own car, just speaking from experience that I personally have tested myself on the dyno. That is more than 90% of the dudes here on CRSX who make all these statements can say.
 

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AWD FTW
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Nice.... Is it loud? Did u use a resonator as well?
it is loud, but i have taken out the back sound deadening. No resonator, which is partially why its so loud at cruising speeds. WOT is amazing as always.
 

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Mangekyou Sharingan!
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I highly recommend the vibrant stealth muffler and super quiet resonator if you are running a 3" exhaust....also get about 3 feet of oval piping from burns and a 90 degree bend of oval piping for clearance that equals or surpasses stock exhaust... thank me later:pimp
 

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LilMikeyBoi
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I highly recommend the vibrant stealth muffler and super quiet resonator if you are running a 3" exhaust....also get about 3 feet of oval piping from burns and a 90 degree bend of oval piping for clearance that equals or surpasses stock exhaust... thank me later:pimp
:thumbsup:
thats exactly what im running and people always tell me they love the sound :)



anyways, K series love 3" exhausts and its been proven many times
i know u dude, and i know ur not a noob when it comes to this...u can honestly make good power running either open header or 3" back...all depending on the tune

but which to choose, honestly comes down to how loud u want the car to be..lol..i turned my car on with an exhaust leak and it was loud as shit..imagine open header..lol

ive seen a thread on here about a guy tuning on open header and made nice power...so it just comes down to taste...but dont expect people to hear u beeping when ur trying to race :p
 
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