exhaust noise?

[s14-d]

hi.. i think it has been about 4 months now, since i purchased my 95 240sx SE. and i am just about to have enough of this exhuast noise. first i thought that the noise is from the heat shields. so i took 2 off. but it doesn't help, so i have my friend looked at it (who is tech at a dealer). and he found out that it was insde the 2nd cat or whatever that center piece is ( that piece is after the o2). and thats where the noise is from. OK. so now.. i got 3 options here:

1. get a used 2nd cat or order it from the deal.. 2. get a cat back exhuast + replace that 2nd cat with a custom piping at a muffler shop. 3.get a muffler, and get the piping done all togther.

Sorry for the long post, thank you.

[91nis240]

muffler w/ custom piping, cheaper and just as, if not more effective then catback exhaust w/ apex hks, greddy etc

[BuudWeizErr]

Heres some news for you. Unless my friend who has an S14 is a complete idiot (which he very well may be), your "cat" is not actually a "cat." It's a dummy cat. It only looks like a cat so that cops don't harass you. Your cat is actually in your exhaust manifold. He told me to get an S14 dummy cat for my car, because it is actually hollow.

This does not apply in Canada, because, apparently that cat is a real cat in Canada. They require two cats.

Can anyone confirm this?

[91nis240]

yes ive heard that from few people about the 2nd cat being hollow, but im an s13 owner so im like 99 percent certain on that. Anyone whos compleltly sure??

[Onizuka]

muffler w/ custom piping, cheaper and just as, if not more effective then catback exhaust w/ apex hks, greddy etc

I wouldn't that...

There is no way a custom exaust from "insert muffler shop name here" will out perform a pre-fab catback (from a big name parts producer) and aftermarket caty.

companies like Apex'i and HKS etc. have dynos to actually test their products to try and get the best results for each vehicle the exaust is made for. And i gaurentee that most muffler shops wont have a mandrel pipe bender which is almost nessecary to get the best results out of a exaust.

I have seen a meinake (spelling?) job and it sucked compared to my apex'i cat back....

your better off buying a name brand exaust.

Just my 2 cents, sorry for the lecture

~matt

[daniel240]

Heres some news for you. Unless my friend who has an S14 is a complete idiot (which he very well may be), your "cat" is not actually a "cat." It's a dummy cat. It only looks like a cat so that cops don't harass you. Your cat is actually in your exhaust manifold. He told me to get an S14 dummy cat for my car, because it is actually hollow.

This does not apply in Canada, because, apparently that cat is a real cat in Canada. They require two cats.

Can anyone confirm this?

this is not true. there is no "fake" or "dummy" cat. it is just a secondary cat. believe me, i have taken it off and looked. ,Hey S14-d, what kink of noise is it making, is it a rattleing noise??? if it is than it is your heat sheild, and that can easily be revoved. those tend to rattle on all s14's and i think s13's are the same way.

[Onizuka]

yes ive heard that from few people about the 2nd cat being hollow, but im an s13 owner so im like 99 percent certain on that. Anyone whos compleltly sure??

well by law (at least in my state) you are only required to have one catalytic converter so why not take it off anyways?

[SilviaLuvr]

my boy asked me a question about his exhaust b4 and i didn'nt know what to tell him. Well my boy has a RSX and he got a thermal exhaust instead of the HKS like i told him to get (again he neglected my opinions 1st i said get the type S and he gets the regular and nw he hates it and now this) the exhaust isn' t that bad i guess but then again everytime when it rains, his exhuast sounds like crap and he asked me what has up wit that and i was like IDK? thats what happens when you get crappy exhaust systems i guess IDK what else to tell ya. so thats my story. any suggestions?

[daniel240]

muffler w/ custom piping, cheaper and just as, if not more effective then catback exhaust w/ apex hks, greddy etc

Well i do agree w Jspec tuner about the cat-backs vs. custom, but really there is not much difference between a good custome exhaust and catback. its not that hard to find a muffler shop that does mandrel bending. and for the $ difference between the 2, its like $200-$300. i took my car to a muffler shop the does mandrel bending, and he put it up on the lift and i came in and looked at it with him. i told him i wanted it as free flowing as possible and he routed it in almost a straight line from the cat back to the muffler. i ordered a muffler for $180 and he charged me $120 for the custom piping and everything. and it works great and sounds awsome, i could feel a difference.

[sixxdeuce]

The second cat IS a dummy cat and I had the exact same problem on my 95, I took off my manifold heatshield and the one over the dummy cat and it did not fix the problem. That noise it very annoying, does it happen at a certain rpm on yours? Anyway, the noise is caused by the exhaust gasses going through the real cat and down the narrow stock pipe and then just hitting that big open area inside the hollow cat. The cheapest fix is to cut a short pipe, the biggest diameter that will fit through the cat and weld it in there, make sure it doesnt stick out past the flanges or it wont seal and you will burn up gaskets. If you have acess to a swedger its alot easier when you swedge the ends so it barely fits inside because you dont have as much space to fill up with the weld. Then use a small grinder to grind and smooth any weld material that sticks out and bolt it back in, the sound is way better and it felt like i gained some torque. And about the custom exhaust vs. name brand, the difference is about half a horsepower IF the tech knows what hes doing with the exhaust. There are ways to make very little restriction, even on crush benders. And if mandrel bends are a must for that half to one horsepower you can just get ubends and cut what ever angles you need for the bends. After working at an exhaust shop for 2 years and seeing how simple it is I would NEVER buy a name brand exhaust, total waste of a couple hundred bucks. Just find a nice sounding muffler you like and have the tubing custom bent.

[daniel240]

i guess some s14's are different because my 96 has a real 2nd cat. and i know there are others that do too. i think it might have to do with where they came from. i think maybe the s14s from canada have fake ones. i know mines not because i toke it off and gutted it, and believe me, its not fake. neither is the 1st cat.

[s14-d]

first off i want to say thank you.. um.. i think i will have to agree with sixxdeuce. since i took of 2 of the heat shields already.. and the one above the 2nd cat and the one in front are the only 2 heat shields left.. so it must be that 2nd cat/ dummy cat. either the cat is a dummy or not doesn't really matters? as long as it is make that noise!! then i will have to do something about it.. but " sixxdeuce " what about getting a new 2nd/ dummy cat? from the dealer or something.. does anyone how much it will cost?since i don't how to weld? and i don't have the machines at home.. so yea.. um.. what about having a muffler shop replace that 2nd/dummy cat with a pipe?

thanks again for helping guys

[96_S14_SE]

Some s14's indeed come with a dummy cat and some with a secondary cat. 97-98's have no issues on this (Ive never once head of it) and the second is 100% a dummy shell. The reason is for the turbo motors not having the first cat, thus they put it there and to save money they use a dummy shell in usdm trim.

Now the S14b (95 - 96) can come with either. All of the auto's Ive seen have had a real secondary cat in conjunction with a precat (single cat on the others). In the manual it also states there are two in certain instances. Mine is an auto and yes has two cats.

Easiest way to tell for all who want to know, is look under the car. The hollow shell is just that a cast iron shell of a cat. The ones with real cats have a heat sheild on them covering the cat. When the sheild is removed (in case a previous owner did to remove rattles) the welded on brackets will still be there. Even if these brackets are cut there will still be evidence of it being there. I bottomed out on a bridge at about 80 a cpl times before they fixed it, and I had the sheild off but mashed the brackets down good. They never came off just got mashed nicely.

[daniel240]

you dont need a muffler shop to take it off. it simply bolts on. just take it off and see if it is a dummy cat or not. i still dont know what kind of noise it is making. is it a rattleing noise?? i know i had rattleing noises and it took me forever to find out what it was.the first time i removed 2 of the heat shields and it didnt help, then later i removed all of them, including the one around the 2nd cat. this fixed the problem. one way you can tell easier is to crawl under and shake or hit your exhaust pipe in different spots and try to find out exactly were its comming from, that is what i did. most muffler shops will not put a straight pipe through the cat because it is illegal and they can get fined like 2500. ive been to 3 different ones and they all told me the same thing. even after i had gutted my 2nd cat. i suggest do it yourself or get i high flow cat, but i still dont see why the hollow cat could by making noises.

[91nis240]

j spec tuner no when i say a custom exhaust is just as good or better than a full after market cat back, i mean that only if its done right. but Liek you said if it done poorly then it worthless. so I bought a apex'i N1 mufler, then i took my car to a quality exhaust only shop. I got mandrel bent 2.5in piping and i was there the whole time the piping was being made. I made sure it was as staright as possible, i got no resonator but kept the cat. After this was done, exhast was the only mod done to my car, and same w/ my cousins 240 (he has HKS HIPER catback) and he siad my exhaust made more horse power than his. Atogether this cost me $330 vs. $450-$525 for an aftermarket exhaust.

[daniel240]

yea thats definately the way to go!