3" exhuast too big for KA na?

[seishidrft]

just wondering if i go with a custom 3 inch exhaust on my kade naturally aspirated, would that cause too much backpressure? ive heard that many people go 3" and have had no loss in gains. some recommendations on pipe size would be much appreciated. and sorry for this dumb question but i forget, does a larger exhause pipe make it louder or quieter? thanks

[drftnassmofo]

well about it being louder or not..that will depend on the size of resonator you use...the longer the resonater the quieter itl be....i think having a 3 " exh...on NA wouldnt have enough backpressure and you'll actually lose 1-2 horsies....but who cares...it sounds teh hotness ehh??imma get 3'' piping on my na but ill be going turbod this june-july.mwahahaha...the 3"es...DO IT UH.....DOO IT

[Bryants95240sx]

well first off the bigger the piping the less backpressure there is. and secondly i have a apexi n1 (3inch) on my NA ka and i gained top end and didnt notice any loss on the bottom end . i dont have any dyno graphs to show it but this has been covered before. AND YES IT SOUNDS AWSOME

[seishidrft]

thanks fellas. im thinkin of goin with hotshot headers and custom 3" straight pipe, with a apexi turbo muffler, (or does straight pipe mean no muffler too? watever, just no cat and all that junk)sound like a good idea?yea, i was gona go turbo KA but i hate the gas i get now with the KA and if i were to throw a turbo on there i dont think i could take it. ill just go ca or sr when the time comes.

[Dattebayo]

Have fun.

But you'll regret it. Because you will now have to spend an as$ load of cash on that custom catalytic converter. Or maybe you dont care about the environment. Or maybe you dont know that the size of a regular catalytic convertor is going to make the pipe taper in and the 3" will be pointless.

Ive been around this forum a wahile and those who do this will lose bottom end torque and create a lot of unnessesary noise. There are alot of threads on this topic and most of the guys complain about it when they've done it.

Its cheaper and smarter to get no more than 2.5" for a N/A KA.

[eddiec]

heres my exhaust evolution. http://www.cardomain.com/memberpage/395215/8

[Bryants95240sx]

[:: orion ::]

Couple things to note:

1) KA's respond well to BIG exhaust...even N/A. 3" is good for your big 'ole 2.4 liter.

2) Backpressure is not needed, nor is it good. Exhaust velocity is good, and with a decent header, the KA has plenty...

3) HS Header + N1 is loud. I mean LOUD!!! The header piping is thin, so lots of noise escapes through there...plus a long, straight 3" pipe...it drones on the highway. FYI...

(Typically, I'd also reccomend a 2.5" mandrel bent exhaust for most 4 cylinders...but people have shown very good gains with 3" exhaust, between 12-16rwhp...with little-to-no loss in low end)

- Brian

[j-z]

i have a 3'' megan racing exhaust on my car and i love it. i did notice some loss down low, but the high end i gained was worth it. i also just recently made a 2.5'' test pipe and that made a big difference up top with a nice gain and no loss down low. my setup is not loud at all. it kinda has a wrx tone to it.

[kamikazestorm420]

i have the blitz nur-spec exhaust and it is also 3". i still have stock headers and a stock cat but that thing is loud...

i did notice loss of torque in the low end but from 5500 on it pulls. when i put the silencer on i gained back the low end i lost (maybe because of the increase in backpressure) but i noticed a loss in my high end.

[deviousKA]

3" full straight pipe short side exit would produce the most gains. Most likely illegal unless you live in some place like idaho.

3" normal setup would be louder than a stock or 2.5" setup, the more quiet the exhaust the more restriction it has. If your going to run a cat, run a large high flow model and dont use any baffled mufflers.

Having no catalytic converter is not necessarily bad for the environment, you can easily produce less environment damaging emissions than most average cars running one. Its called tuning.

[Dattebayo]

ha ha ha ha ha hah aah ahhhhh ha.

why dont you just run no pipe at all? How about just having the exhaust just ome straight out of the hood?

[nismo1003]

is It true that the longer the resonater the quieter

[Bio_Hazard]

i have hotshot headers and a full 3" with no cat, it's very loud i've been told you can hear me form about a mile away at WOT. as for the power loss its not that bad mabey a loss of 4 or 5on the low end, top end increased. I'm geting ready for an RB25DET swap thats why i have this set up.

[Nissan-S14]

I also have the Blitz Nur-R, its actually a little bit more then 3" its about 3.2 to be exact and to be honest in 1/4 i did gain, from 15.9 i went to about 15.7. (Other factors may have caused) But after the exhaust my car doesnt run slower then 15.7 And if you think Apex N1 is loud, well thats amost stock compared to Blitz, My friend has one on his 95, we compared them both, the Blitz is a lot more louder, I believe Blitz is about 110-112DB at peak compared to 94-96 at stock and Apex at 106db

[ddgsxr504]

I have a 95 with a hotshot header, (Greddy's Sucked ***, kept cracking on the welds), and an Apexi N1, as far as a catalytic converter I tossed that piece of S*$# and put in a 2.5" test pipe. It sounds so much better and is less restrictive. As far as tapering goes for installing a aftermarket cat the hotshot header is already about 2 and some change and a test pipe will fit is very nicely. I got the test pipe from ebay for $30. You will lose some low end torque up to about 2800rpms but the top end makes it worth it. And as for polluting the environment, 1. A cat is useless until it warms up anyway and 2. Tell that to all those old straight piped or dump piped muscle cars still on the road running carbs that just dump an *** load of gas into the intake!

[pnissan2]

What is the legal exhaust noise limit?

[j-z]

ok, i just installed an ebay short ram intake on my car and my low end is back YAAYYYY!! i didnt think that adding it on would make such a big difference because i already had a cone filter on the stock intake. it pulls much harder every where on the entire rev band. im just adding this as an addition to my post up ^ there. now i can say that with my 3'' exhaust and 2.5'' test pipe, compared to stock, i feel no loss on the lower revs at all. groovy baby, yeah!

[keepingthe240]

I have a greddy 2.5 catback (on the car) and a n1 (leaning against the wall in my house) Anyway, the 3 inch has a different bolt pattern. The 2.5 inch gasket doesn't fit on the 3 inch. Thus the n1 wouldn't fit on car unless i change the "dummy cat"

[GEO]

http://www.htsinstalls.com/del...e.avi

Thats my car at WOT with the Apexi N1 and AEM SHort RAM

[Nissan-S14]

What is the legal exhaust noise limit?

"DECIBEL (dB)- A unit for measuring the volume of a sound, as determined by a sound testing instrument. The NYS Vehicle and Traffic Law sets unacceptable noise levels at between 72 dB and 90 dB. For purposes of this law a decibel level exceeding 90 dB shall be a nuisance noise. "

Thats for NY, Im not sure about other states. But its about the same, but in NY they dont give a sh-t about noise or pollution or smog. Or what kinda engine you have, as long as you have a registration sticker, inspection sticker and plates..

There are very very few after market exhausts that are smog legal and are under legal DB level. Even though some say they are, you have to read the fine print, which may state assuming your car is new and you have no other mods, etc. etc.

[AelSic]

How does the test pipe affect the O2 sensor?

[GEO]

In order to have a test pipe I beleive you need to get rid of the dummy cat which houses the O2 sensor.

[Bio_Hazard]

the test pipe i have has a place for your 2nd o2 sensor on it

[240sxHitman]

Thats for NY, Im not sure about other states. But its about the same, but in NY they dont give a sh-t about noise or pollution or smog. Or what kinda engine you have, as long as you have a registration sticker, inspection sticker and plates..

well may be in bk but in long island i got a ticket for noise i guess its just nassau cops

[EstoMax]

i have a 3 inch catback with a highflow cat , custom bent and with a pro1 (some generic i guess?) muffler

came with the car when i got it

i like it its quite loud but im used to it

max

[TheOne]

bit off topic but.....any of ya got the RS-R exmag catback installed? got any sound clips?

[stillmatic]

N/A KA's don't like backpressure. It's been dyno proven.

Dyno 1 (stock exhaust, hi-flow 2.5" cat, obx header, asp pulley, ebay intake, fidanza flywheel, advanced timing)

Dyno 2 (same mods except for open cat and more advanced timing)

Note: Best pull was 165whp

BTW, the car is running high 14's all motor

[DarkStar]

I've got nismo headers, cat-co cat welded to a Greddy evo 3 inch exhaust it its not too loud unless I'm WOT. And even then rice can hondas are still alot louder. Nice high-end power (at 4k it roars to redline!), didn't really notice too much difference in the bottom-end, good or bad.

[CDE]

Holy crap, that's a huge difference in those dyno's...