Custom exhaust building...

[Odysseus]

So Im a senior in highschool and for my senior project my shop teacher is going to help me fabricate an exhaust for my 240sx. I have a stock KA24E so I dont want it to be obnoxious and loud since I cant back anything up but I do want a nice solid aggressive sound.

I plan on using 2.5" tubing the whole way and ending with an HKS Hi-Power muffler in 60mm. That is something Im pretty set on since I really like the sound.

I dont know what to do before I get there though. Should I go catless? Or highflow cat? Can you point me in the direction of a good highflow cat?

Should I use a presilencer or resonator?

I plan on doing this manifold back. Im pretty sure my exhaust manifold is good but Ive been told I have an exhaust leak in my EGR tube.

If you guys could give me some insight and guidance Id really appreciate it. Thanks!

[SidewayZ-s14]

You could go catless, but your car will SMELL like a lawnmower. IMO, id stick with a cat.
The HKS Hi Power exhaust does have a nice purr to it! I give the thumbs up on that.

Presilencer....booo! :)

[Steveohoes]

go 3 inch and put a box resonator.
Look online at exhaust that are being sold and just use those as reference.

[Odysseus]

3" is too big IMO. Im pushing like 110 WHP on my KA at best haha..

So cat it is. Anyone have a highflow one they reccomend? I dont really wanna use my old one.

[s13 @ fullboost]

magnaflow makes some cool ones

[burnsauto]

catco as far as a high flow cat.

[SoguRacing]

i would stick 2.5" and go with a resonated test pipe but leave room for a cat when you go to smog.

[nissandr1ft]

I run full 3" header back with a catco cat, vibrant ultra quiet resonator, and vibrant dual tip 20" long muffler. Even though I run a header its pretty quiet, and not raspy... very deep, and doesn't drone on the interstate.

[Odysseus]

i would stick 2.5" and go with a resonated test pipe but leave room for a cat when you go to smog.

I dont have to smog my car :) hahaha

I have the emissions sheet thats good for 2 years I think though. From when I bought the car.

[SidewayZ-s14]

I dont have to smog my car :) hahaha

I have the emissions sheet thats good for 2 years I think though. From when I bought the car.

I think he means for WHENEVER you have to smog your car! :hsdance:
Goodluck on the exhaust!

[sleepy_s13]

Sogu has got a good idea, Cans are loud on NA Cars.

[Odysseus]

I think he means for WHENEVER you have to smog your car! :hsdance:
Goodluck on the exhaust!

Sorry, I worded that weird. I meant that where I live, we dont have to smog our cars PERIOD.

Im almost thinking of doing a 3" now so I dont have to do it when I get an SR.

[soreballz]

If you're going 3inch, then...
3inch piping, resonated test pipe, 18 inch long perforated core resonator, and a canister of your choice. Just remember that the bigger the can, the quieter the exhaust will be, and don't cheap out on the canister. Cheap ebay cans usually don't have any packing in them, so they're raspy and loud as fuck.

[Odysseus]

HKS Hi-Power for sure. Possibly a Megan Resonated testpipe? I need to find out if the tubebender Ill be using can do 3"

[Jonnyblaze]

I have a 3in unresonated pipe from the cat back with a Hyper Medallion muffler. Even with the huge muffler it's still a little too loud for my taste. If you go 3in I highly recommend you resonate it.

[Addicted2Kouki]

I have a 3in unresonated pipe from the cat back with a Hyper Medallion muffler. Even with the huge muffler it's still a little too loud for my taste. If you go 3in I highly recommend you resonate it.

Its only loud because you are NA and basically have a straight pipe to a big can from the cat, back.

[superduner]

The real question is "do you care about cops" ?

if your answer is yes. i say you go 21/2 piping get a high flow car and resonator. you will still have the sexy purr because of the exhaust at the very top of the piping. however there wont be no reason for cops to give you a (modified exhaust and excessive noise fix a ticket)

if your answer is NO i say you STILL go for 21/2 get a high flow car but no resonator. and throw in a DC header. ;) fairly cheap and pending carb legal. (i believe)

reason i say you have a cat is to help protect our environment just a bit ;), so your exhaust wont smell completely like gASS, and so theres no reason for you to fail your smog test 2 years from now.

just my 2 cents :)

[Odysseus]

Im pretty sure that the local cops wont care much since there are 4X4's running around without any exhaust at all. Straight out the headers haha

I dont want crazy crazy rice rice loud but I dont wanna have to do this twice. And I dont really wanna buy headers for my KA since I dont plan on having it for more than another 8 months.

[soreballz]

If you're going 3inch, then...
3inch piping, resonated test pipe, 18 inch long perforated core resonator, and a canister of your choice. Just remember that the bigger the can, the quieter the exhaust will be, and don't cheap out on the canister. Cheap ebay cans usually don't have any packing in them, so they're raspy and loud as fuck.
Once again...

[Dr.Doom]

Once again...

Tis true. Based from my own personal experience.

[Odysseus]

What really is the point of a resonated test pipe?

[soreballz]

Well, if you plan on going catless, then the resonated test pipe is simply an extra resonator to help smooth out the exhaust tone. With an NA KA, you need it to avoid the raspy tone.

[dan240]

... and throw in a DC header. ;) fairly cheap and pending carb legal. (i believe)

DC has had their header pending CARB for ~5 years (longer?). I wouldn't count on it.

Doesn't sound like it matters for the OP anyway but thought I should throw that up here.

Best,
Dan

[BoostedCoupe]

If you'r sticking to factory header. then just run 3" all the way back to a good canister. Make sure the piping is as straight as possible. Stretch the hangers if you have to. DO NOT!!! put bends in it like the factory exhaust has. it will sound like shit. i have already tried it. and to the people that say dont do 3" on n/a. shut that shit up the ka loves 3" NEED PROOF? here ya go.http://www.zilvia.net/f/tech-talk/177055-na-ka24de-motors-love-breathe-my-stock-motor-dyno-pics.html
now go build your exhaust. Shouldnt take but an hour or so.

[Odysseus]

Well, if you plan on going catless, then the resonated test pipe is simply an extra resonator to help smooth out the exhaust tone. With an NA KA, you need it to avoid the raspy tone.

The plan wasnt to go catless, it was to do something else instead of my stock cat. I either want a high-flow or I guess a resonated testpipe. I guess Ill go with that Megan.


If you'r sticking to factory header. then just run 3" all the way back to a good canister. Make sure the piping is as straight as possible. Stretch the hangers if you have to. DO NOT!!! put bends in it like the factory exhaust has. it will sound like shit. i have already tried it. and to the people that say dont do 3" on n/a. shut that shit up the ka loves 3" NEED PROOF? here ya go.http://www.zilvia.net/f/tech-talk/177055-na-ka24de-motors-love-breathe-my-stock-motor-dyno-pics.html
now go build your exhaust. Shouldnt take but an hour or so.

No bends huh? I thought the bends are supposed to quiet it down? I pretty much planned on following the factory exhaust route since they probably put it there for a reason. We'll see once I get underneath it though.

You were putting down nice numbers for a NA KA. Props.

[dori_sil8t]

i say 3" magnaflow dog. 3" back with dual blast pipes..thats just me tho

[atutt]

So Im a senior in highschool and for my senior project my shop teacher is going to help me fabricate an exhaust for my 240sx. I have a stock KA24E so I dont want it to be obnoxious and loud since I cant back anything up but I do want a nice solid aggressive sound.

I plan on using 2.5" tubing the whole way and ending with an HKS Hi-Power muffler in 60mm. That is something Im pretty set on since I really like the sound.

I dont know what to do before I get there though. Should I go catless? Or highflow cat? Can you point me in the direction of a good highflow cat?

Should I use a presilencer or resonator?

I plan on doing this manifold back. Im pretty sure my exhaust manifold is good but Ive been told I have an exhaust leak in my EGR tube.

If you guys could give me some insight and guidance Id really appreciate it. Thanks!

Stick with 2.5 all the way through. Get a high flow cat. But a real high flow cat. Do some serious research on high flow cats. You'll be surprised what you find. As some high flow cats flow worse than your OEM one does (ie, some of your fave name brands).

3'' on an N/A KA is overkill and is pretty useless. I personally run 2.25 ID from the manifold back. It's quiet running around town. A nice low grumble. But when I open it up it screams at me. :)

[soreballz]

3'' on an N/A KA is overkill and is pretty useless.
Wrong. Wrong. Wrong. Wrong. Wrong. Wrong. Wrong.

Get the point yet? You're WRONG.

N/A KA's LOOOOOOVE 3 inch piping. This is FACT, and has been proven time and time again on dynos. Plus, the OP said he's gonna be swapping in an SR, and he doesn't want to re-do the exhaust.

[BoostedCoupe]

The plan wasnt to go catless, it was to do something else instead of my stock cat. I either want a high-flow or I guess a resonated testpipe. I guess Ill go with that Megan.




No bends huh? I thought the bends are supposed to quiet it down? I pretty much planned on following the factory exhaust route since they probably put it there for a reason. We'll see once I get underneath it though.

You were putting down nice numbers for a NA KA. Props.

That is not my car nor dyno numbers. just info that is on the site.
Yeah no unnesscary bends. Im telling you right now if you make it bend just like the factory exhaust and put a can on it you will hate it. Make it as straight as possible. Look at all the aftermarket catbacks. They do not have alot of bends. I have 3" on my ka and it does not have hardly any bends and it dosent get loud at all. IF you put them factory bends in it i gurantee you, you will go back and redo it. Dont listen to these people saying 2.25 good god thats factory size piping. 2.5 is ok but its not the best just do 3" Just because the piping is bigger dosent mean it is louder. Look at the trucks that have small ass pipes on them they are really really loud. Now look at the trucks that have normal size dual tips they are not as loud. Just do it right or do it twice. Im so shocked no one has came in this thread and said the whole backpreassure myth.

[Odysseus]

So as little bends as possible...Got it. Anyone wanna crawl under their car and show me a good path to run my piping? :)

[Odysseus]

Getting ready to order the 3" resonated testpipe and the large HKS muffler. Any objections?