Headers are in but strange noise from the Tail

I tried the headers with test pipes, non resonated open test pipes... it was not good at all. I went back to original cats & then it was just a bit louder & raspier than before the headers to begin with, so the headers add some volume & rasp even with the stock cats

I have no idea how much louder it will be with high flow tiny cats tbh... I'm afraid to find out cause it's almost too loud as-is with the stock cats... I'm considering going with the high flow cats & then adding a set of supertraps as tailpipes... at least then I can tune it down to an acceptable level I think...
 
raymond said:
Turbo,

Wich mod did you do on your cats wich you didn't like...?? I now have the DC headers on as well with the Kakumei Y-pipe and am thinking on changing my cats as well,but then with metallic cats and no dummy's or so. But am doubting as i do not want the sound to change that much and give it a more "Tin" sound. But do think i need it to get more out of it as for performace.

Any suggestions...?? ( of course all suggestions from everyone are welcome )
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Just FYI, I asked a muffler shop that works on Hot-Rods, and they advised against replacing the Cats. They said that Infiniti/Nissan uses Hi-flow Cats already and the amount of air restriction caused by the OEM Cats are not much. According to them, I'd be throwing money away if I replaced them.

Also, creating higher flow on the back end causes low end power loss. This is according to Precision Z Today. Unless you create more boost on the front end, you'll only gain HP on the higher RMPs over 4K.

I've noticed this that when I get to about 4.5, all of a sudden, it's like a switch turns on and there is a kick.:eek:
 
turbocad6 said:
... I'm afraid to find out cause it's almost too loud as-is with the stock cats....
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+1 I have my stock cats on now and I think its crazy loud @ WOT. When Im at cruising speeds its just a tad louder than stock.
 
yeah, last weekend my motherinlaw was complaining that she had a headache in the back seat... asked if I did anything to the car:4tongue:... this weekend she said, oh, did you fix something? it's much better now.... only difference was last weekend I was really getting on it at times & this weekend I just pussyfooted it...
 
turbocad6 said:
yeah, last weekend my motherinlaw was complaining that she had a headache in the back seat... asked if I did anything to the car:4tongue:... this weekend she said, oh, did you fix something? it's much better now.... only difference was last weekend I was really getting on it at times & this weekend I just pussyfooted it...
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Same thing happend to me this weekend. I was going though Beverly Hills and a Cruiser was following me. So I was shiftin on 3K mark so they wouldn't notice the Loudness of the Exhaust. Also, everything I go into one of these indoor parking lots, I keep setting off Alarms, left and right.:laugh:
 
raymond said:
Can anyone of you tell me wich is louder.....the HKS or Nismo cat back system...??
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In order to know for sure, you'd have to listen to both in the same environmental conditions. Also the sound changes depending on the Intake as well. But here's what I found on Youtube for you.

Again, you cannot judge only by these. Maybe you can look for more clips, or maybe some of the guys here can do a side by side for you.

Also, please remember that the sound changes after a few weeks of burning in period and also remember that Nismo comes with a bigger Y-pipe which also affects the over all results.

HKS Legamax
YouTube - FX35 HKS LEGAMAX EXHAUST...

Nismo
YouTube - Infiniti FX35 Nismo Exhaust
 
FXtion said:
Just FYI, I asked a muffler shop that works on Hot-Rods, and they advised against replacing the Cats. They said that Infiniti/Nissan uses Hi-flow Cats already and the amount of air restriction caused by the OEM Cats are not much. According to them, I'd be throwing money away if I replaced them.
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I wish I read this last week :frown:...

Sorry to bring back an old thread, but I was searching :tongue: about rasp, and came across this thread.

I have cat back UTR exhaust system on my FX, and thought it'd complement the system if I got their HFC's also...wrong !!! :tdown:. I had some rasp before the HFC's at higher rpm's, at wot. Now...non stop embarresing rasp :mad:. It's so bad that I'm ashamed to hit the gas pedal, it sounds like tin cans are being ripped apart. On a positive note though, my mpg went up to as high as 22 mpg due to driving in auto mode, and driving like a granny :laugh:.

Needless to say HFC's are coming out this week, can't stand them. Contacted UTR about the problem but nothing good came out of it, just wasted money for nothing.

So, if anybody wants to increase their mpg, I'm selling my practically new HFC's :rofl::laugh:.
 
Did you have to take out your entire exhaust or just the Cats. It's not uncommon to put the gaskets in the wrong place or not get them exactly centered.

My problem was that the where not centered so there was restricted flow.

Take out just the gaskets and see if you have burn marks on them. If so, the were not centered properly.
BIGTURK said:
I wish I read this last week :frown:...

Sorry to bring back an old thread, but I was searching :tongue: about rasp, and came across this thread.

I have cat back UTR exhaust system on my FX, and thought it'd complement the system if I got their HFC's also...wrong !!! :tdown:. I had some rasp before the HFC's at higher rpm's, at wot. Now...non stop embarresing rasp :mad:. It's so bad that I'm ashamed to hit the gas pedal, it sounds like tin cans are being ripped apart. On a positive note though, my mpg went up to as high as 22 mpg due to driving in auto mode, and driving like a granny :laugh:.

Needless to say HFC's are coming out this week, can't stand them. Contacted UTR about the problem but nothing good came out of it, just wasted money for nothing.

So, if anybody wants to increase their mpg, I'm selling my practically new HFC's :rofl::laugh:.
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when I did my headers I also put in my test pipes... that's exactly what I got, perfect description is; it's so bad your embarrased to step on the gas :laugh: raspy like a mo fo, ricer teritory for sure, especially with headers & duals, not for the fx... ripped them back out the NEXT DAY! & went back to stock cats.it was undrivable, like you said, you had to granny it & avoid steping on the gas at all costs :laugh::laugh::laugh:

I always wondered about how much that might come back with high flow cats so I stuck with the stock cats so far, but I think with FI a metallic cat is almost manditory if you want to really push it hard? stock cats might start to have problems above 1,200 deg or so... not looking foward to that, gonna have to add more mufflers for sure at that point I think :tongue:
 
FXtion said:
Did you have to take out your entire exhaust or just the Cats. It's not uncommon to put the gaskets in the wrong place or not get them exactly centered.

My problem was that the where not centered so there was restricted flow.

Take out just the gaskets and see if you have burn marks on them. If so, the were not centered properly.
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I didn't remove the whole system, just the cat's. Just took out the bracket that holds the clips for the O2 sensors in place, than removed the cat's. I think holes in the gaskets and the studs/bolts fit pretty flush, so I don't think there is room for them to move around. But I will check just t o make sure, thanks for the suggestion. It'd be great if I could make this work because otherwise I'm stuck with these HFC's that I can't use.

Yea John, I'm the king ricer right now :laugh:......:frown:.
 
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UTR system is a 3" single pipe also.

Just took out the UTR mid pipe and the muffler, and threw the stock one's back on just to test to see what would happen. So far rasp is less, but still there at high rpm's. I'll see what happens on the way home tonight. My father says to give it some time, that cat's have to break in. But the problem is, I don't know if I can live with that for a month :rolleyes:. I'll keep you guys updated.
 
I remember with mine, some of the noise was coming from the mid-pipe hitting the brace in the middle. The mechanic loosened the Cat bolts, put a jack under the Y-pipe, and then tightened the bolts. The rattle was gone.
BIGTURK said:
UTR system is a 3" single pipe also.

Just took out the UTR mid pipe and the muffler, and threw the stock one's back on just to test to see what would happen. So far rasp is less, but still there at high rpm's. I'll see what happens on the way home tonight. My father says to give it some time, that cat's have to break in. But the problem is, I don't know if I can live with that for a month :rolleyes:. I'll keep you guys updated.
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