# Confused about exhaust size **URL:** \ **Category:** SON240sx Automotive\ **Created:** [May 21, 2005, 8:11pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848 "2005-05-21T20:11:21Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![albguy40](https://avatars.discourse-cdn.com/v4/letter/a/e19b73/32.png) [@albguy40](https://forums.speedlife.net/u/albguy40)\ **Post date:** [May 21, 2005, 8:11pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/1 "2005-05-21T20:11:21Z")
Guys what do you think is the perfect diameter for an exhaust for a 240 with a ka24de and mostly stock. I want it to sound LOUD, and i mean really loud (No cat or resonators, just muffler). ---
**Author:** ![DTS](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@DTS](https://forums.speedlife.net/u/DTS)\ **Post date:** [May 21, 2005, 8:13pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/2 "2005-05-21T20:13:52Z")
_I am Scott. I am a gomer. (see [urbandictionary.com](http://urbandictionary.com) for definition if you are unfamilar with this term)_ Edited by iQuABoB - Quit being a tool ---
**Author:** ![rotorkami\_wa](https://avatars.discourse-cdn.com/v4/letter/r/e36b37/32.png) [@rotorkami\_wa](https://forums.speedlife.net/u/rotorkami_wa)\ **Post date:** [May 21, 2005, 9:15pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/3 "2005-05-21T21:15:14Z")
'40- running no cat is can and will get you a sizeable tickit… in the 4 figures range. 95 db is the legal limit and cops will go after you for anythig close to that … your best bet is to get a high flow cat , say 380cfm or better, a stainless mesh surface mount cat is probably the best chioce. try to get as small a lenght of cat as possible… the longer the exhaust has to stay IN the cat the slower it will be come… so a short high flow car 100cel to 180cel in the proper diameter is perfect. As for an exhaust, cheap ones are loud and usually untested for ‘tune’ NA’s require allot of tunning in the exhaust for peak performance, get yourself something that is moderatly priced, magnaflow make a street-race setup that is a striaght through design this sill be your loudest option, the quieter option is a baffled-open exhaust whee you have a maze that the gas has to pass thorugh and after that you have the classic packed muffler where the exhaust needs to pass thorught the glass pack to get out of the muffler, this is your last and lowest power option but it’s th quietest… ---
**Author:** ![DarkForceJackal](https://avatars.discourse-cdn.com/v4/letter/d/b38774/32.png) [@DarkForceJackal](https://forums.speedlife.net/u/DarkForceJackal)\ **Post date:** [May 21, 2005, 9:28pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/4 "2005-05-21T21:28:28Z")
If you want it loud and with ideal diameter for performance, I would say somewhere in the 2.5" area would be a good bet. ---
**Author:** ![rotorkami\_wa](https://avatars.discourse-cdn.com/v4/letter/r/e36b37/32.png) [@rotorkami\_wa](https://forums.speedlife.net/u/rotorkami_wa)\ **Post date:** [May 21, 2005, 10:49pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/5 "2005-05-21T22:49:45Z")
2.5" exhaust is rated for a flow up to a bit over 300hp… with is pretty much double what the stock motor will put out… 2.25" should be the biggest you look at. flow velocity stays high and cavitation ( that that crap ass popping you ehar from sunfires with a too big an exhaust ) will be almost non exsistant. I deally to et the best flow and therefore tone from your muffler mandrel bent mild steel with a ceramic coating inside and out would be your best option for perfomrance at or around OEM hp. just a clean header and good cat will make all the difference… 2.5" is just too big to do anything and it actualy takes around performance at the low end. ---
**Author:** ![DTS](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@DTS](https://forums.speedlife.net/u/DTS)\ **Post date:** [May 22, 2005, 7:56am UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/6 "2005-05-22T07:56:22Z")
get a full 3" youll make like 7 whp and wont loose much low end some guy made 14 whp with a full 3" on a stock ish KA go search on FA and you will see [forums.freshalloy.com](http://forums.freshalloy.com) ---
**Author:** ![MrSkinny](https://avatars.discourse-cdn.com/v4/letter/m/59ef9b/32.png) [@MrSkinny](https://forums.speedlife.net/u/MrSkinny)\ **Post date:** [May 22, 2005, 8:39am UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/7 "2005-05-22T08:39:52Z")
im running 3 inches on a KA. u wont regret it. dont believe everything u read. ---
**Author:** ![NeveR](https://avatars.discourse-cdn.com/v4/letter/n/e95f7d/32.png) [@NeveR](https://forums.speedlife.net/u/NeveR)\ **Post date:** [May 22, 2005, 9:15am UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/8 "2005-05-22T09:15:21Z")
lol @ gomer: Medical slang for a patient who “has lost–often through age–what goes into being a human being” (quote from Samuel Shem’s “The House Of God”). Typically an old demented noncommunicative patient. Stands for “Get Out Of My Emergency Room”. ---
**Author:** ![rotorkami\_wa](https://avatars.discourse-cdn.com/v4/letter/r/e36b37/32.png) [@rotorkami\_wa](https://forums.speedlife.net/u/rotorkami_wa)\ **Post date:** [May 22, 2005, 9:49am UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/9 "2005-05-22T09:49:12Z")
very true, don’t believe everything you read. However, if you read the RIGHT books then ou can do the math for yourself very easily and get the right answer for youself. however if you’d like to see a basic chart of HP-exhaust dia. then look on page 133 of corky bell’s ’ Maximum Boost’, you’ll notice that 200hp is right at the 2 1/8" mark. and 300 is actully around the 2.5" mark, ( my bad) . If your looking for the math on it page 61gives you the lead up and 62 will give you the equation and an example… Maximum boost is regarded as the best book out there for basic to intermediate knowledge on turbos / and the associated parts ( exhausts included ). > [@MrSkinny](#): > > im running 3 inches on a KA. u wont regret it. dont believe everything u read. ---
**Author:** ![DarkForceJackal](https://avatars.discourse-cdn.com/v4/letter/d/b38774/32.png) [@DarkForceJackal](https://forums.speedlife.net/u/DarkForceJackal)\ **Post date:** [May 22, 2005, 3:02pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/10 "2005-05-22T15:02:46Z")
> [@rotorkami wa](#): > > very true, don’t believe everything you read. > > However, if you read the RIGHT books then ou can do the math for yourself very easily and get the right answer for youself. however if you’d like to see a basic chart of HP-exhaust dia. then look on page 133 of corky bell’s ’ Maximum Boost’, you’ll notice that 200hp is right at the 2 1/8" mark. and 300 is actully around the 2.5" mark, ( my bad) . If your looking for the math on it page 61gives you the lead up and 62 will give you the equation and an example… Maximum boost is regarded as the best book out there for basic to intermediate knowledge on turbos / and the associated parts ( exhausts included ). > > [quote=MrSkinny]im running 3 inches on a KA. u wont regret it. dont believe everything u read. [/quote] This is true rotorkami wa, i’ve got & read that same book. But keep in mind, all we know is that he wants it LOUD. So heck, maybe even 2.5-3.0" may be what you’re looking for albguy40, just understand that for balanced PERFORMANCE, it seems 2 1/4" in fact might be the best bet. ---
**Author:** ![rotorkami\_wa](https://avatars.discourse-cdn.com/v4/letter/r/e36b37/32.png) [@rotorkami\_wa](https://forums.speedlife.net/u/rotorkami_wa)\ **Post date:** [May 22, 2005, 6:06pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/11 "2005-05-22T18:06:02Z")
loud just means you need to use a nice thin wall stainless and a straight through exhaust… but be prepared to be targeted… your only allowed to be LOUD if your on a bike, muscle car, 4x4, street rod, or the odd perforated muffler family sedan… but anything that looks ‘compact’ is NOT allowed to be LOUD… nice to see the police being so even and non biased :roll: I’ve noticed that cops will drive right by harleys that produce serious sound levels… i don’t think my rotary with an open header could make that much noise… yet I’ve been ’ hit up’ for noise already … and I run OEM exhuasts!!! ---
**Author:** ![SHIFT\_KA24DET](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@SHIFT\_KA24DET](https://forums.speedlife.net/u/SHIFT_KA24DET)\ **Post date:** [May 22, 2005, 11:32pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/12 "2005-05-22T23:32:31Z")
I made 12whp with the GP Sports 3" and a highflow cat. ---
**Author:** ![DarkForceJackal](https://avatars.discourse-cdn.com/v4/letter/d/b38774/32.png) [@DarkForceJackal](https://forums.speedlife.net/u/DarkForceJackal)\ **Post date:** [May 23, 2005, 2:32am UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/13 "2005-05-23T02:32:16Z")
> [@SHIFT\_KA24DET](#): > > I made 12whp with the GP Sports 3" and a highflow cat. Nice! KA-T? PSI? Or N/A? ---
**Author:** ![SHIFT\_KA24DET](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@SHIFT\_KA24DET](https://forums.speedlife.net/u/SHIFT_KA24DET)\ **Post date:** [May 23, 2005, 11:51am UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/14 "2005-05-23T11:51:09Z")
> [@DarkForceJackal](#): > > [quote=SHIFT\_KA24DET]I made 12whp with the GP Sports 3" and a highflow cat. Nice! KA-T? PSI? Or N/A?[/quote] This was last year N/A This year 3" is to small, I’m running a full 4" HKS Exhaust… ---
**Author:** ![DarkForceJackal](https://avatars.discourse-cdn.com/v4/letter/d/b38774/32.png) [@DarkForceJackal](https://forums.speedlife.net/u/DarkForceJackal)\ **Post date:** [May 23, 2005, 1:02pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/15 "2005-05-23T13:02:33Z")
Classy! 8) ---
**Author:** ![ADAM](https://avatars.discourse-cdn.com/v4/letter/a/4af34b/32.png) [@ADAM](https://forums.speedlife.net/u/ADAM)\ **Post date:** [May 26, 2005, 8:22am UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/16 "2005-05-26T08:22:42Z")
i made 23rwhp and 32ftlbs going from a 2.5 to a 3inch on my turbo car 🙂 i would go with 3 inch in case you want to go turbo later IMO ---
**Author:** ![Uniac](https://avatars.discourse-cdn.com/v4/letter/u/34f0e0/32.png) [@Uniac](https://forums.speedlife.net/u/Uniac)\ **Post date:** [May 26, 2005, 2:19pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/17 "2005-05-26T14:19:50Z")
from my experiance the 3" on a NA ka is way to loud…but if you have an annoying GF like i did, who loved to talk…even if she yells at you, you won’t beablt to make her out…downside is limping thru your neighbourhood in 5th at 10km/h trying not to wake everybody up. set of car alarms at idle DO NOT USE flowmaster for NA EXHAUST ---
**Author:** ![MrSkinny](https://avatars.discourse-cdn.com/v4/letter/m/59ef9b/32.png) [@MrSkinny](https://forums.speedlife.net/u/MrSkinny)\ **Post date:** [May 26, 2005, 2:48pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/18 "2005-05-26T14:48:20Z")
i got 3 inch on my ka with a high flow cat into a tanabe racing medallion with silencer. nice growl not loud. ---
**Author:** ![TekVicious](https://avatars.discourse-cdn.com/v4/letter/t/d9b06d/32.png) [@TekVicious](https://forums.speedlife.net/u/TekVicious)\ **Post date:** [June 1, 2005, 2:58am UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/19 "2005-06-01T02:58:36Z")
I made a full2.5" exhaust on a KA24de powered 240sx. No cat, just straight through N1 style “muffler” . Nice deep tone at idle. Louder than hell at full howl. Scary arrest me loud. I had tried to talk the young client into a 2.25" exhaust but this had fallen on deaf ears. The one HP that you might gain up top will not be worth the 2-3 HP you might lose below 5000rpm. On any street car I’d definitely go smaller than 2.5" if I had a straight flow muffler and no cat. I could expand on scavenging and throttle response and reversion, but I know you won’t listen to me. I say 2.25" and a decent header. ---
**Author:** ![J\_Camel](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/j_camel/32/5499_2.png) [@J\_Camel](https://forums.speedlife.net/u/J_Camel)\ **Post date:** [June 1, 2005, 2:54pm UTC](https://forums.speedlife.net/t/confused-about-exhaust-size/85848/20 "2005-06-01T14:54:04Z")
I got a full 3inch Fujitsubo leget R. I wasn’t going to install it until i got the SR done, but if i can find the right silenser I’m going for it. (ka24e) Would any silienser fit or do I have to get one from Fujitsubo? [Next page](https://forums.speedlife.net/t/confused-about-exhaust-size/85848.md?page=2)