Another Pre-cat gut thread
09-20-2011, 04:05 PM
#1
Another Pre-cat gut thread
It seems like the thing to do nowadays.
I am planning to gut my pre-cats this weekend. One of the two is bad for sure as I can hear rattling. The question is by how much does the sound change? I want to hear from someone who has done it. Is there a drone at highway speeds? Anyone regret gutting their precat because it sounds so raw?
I am planning to gut my pre-cats this weekend. One of the two is bad for sure as I can hear rattling. The question is by how much does the sound change? I want to hear from someone who has done it. Is there a drone at highway speeds? Anyone regret gutting their precat because it sounds so raw?
09-20-2011, 04:08 PM
#2
It seems like the thing to do nowadays.
I am planning to gut my pre-cats this weekend. One of the two is bad for sure as I can hear rattling. The question is by how much does the sound change? I want to hear from someone who has done it. Is there a drone at highway speeds? Anyone regret gutting their precat because it sounds so raw?
I am planning to gut my pre-cats this weekend. One of the two is bad for sure as I can hear rattling. The question is by how much does the sound change? I want to hear from someone who has done it. Is there a drone at highway speeds? Anyone regret gutting their precat because it sounds so raw?
really?
Let's see how this flies for now...
If you have do not have any other exhaust modification, you will not notice much if anything in the sound department. I had headers with stock exhaust for years and never noticed anything different in sound albeit a slight bit of tone.
So please, give details on your car, modifications, etc.
09-20-2011, 04:13 PM
#3
I am also putting installing a y-pipe. my stock flex section is coming apart. I do have a resonated test pipe off ebay. Y-pipe is unknown brand. I have a 2001 SE.
So it will be stock exhaust manifold + gutted precats + y-pipe + resonated test pipe + stock muffler.
So it will be stock exhaust manifold + gutted precats + y-pipe + resonated test pipe + stock muffler.
09-20-2011, 04:16 PM
#4
It's when you get a 3" exhaust is when things get loud, and of course it also depends a lot on how you finish it (muffler size and style) when not going 3".
09-20-2011, 04:40 PM
#7
Senior Member
Join Date: Jan 2010
Location: Denver, CO
Posts: 1,396
if you gut your cats/pre cats or put in test pipes then your exhaust may get a bit raspy, it may not if you have a nice resonator in there. What it will almost always do is give your exhaust that popping noise as you decelerate. If you have a full exhaust the noise will be amplified and you WILL notice the backfiring.
Unless you are boosted/blown you wont notice a power difference. It will slightly free up the exhaust but not enough to notice without having F/I.
That being said, im happy i put a test pipe in, makes the car sound a little better I think hah. As for emissions? Im from florida so... no emission laws haha
Edit: stock exhaust, you shouldnt hear or feel a difference. If anything, itll be raspier
Unless you are boosted/blown you wont notice a power difference. It will slightly free up the exhaust but not enough to notice without having F/I.
That being said, im happy i put a test pipe in, makes the car sound a little better I think hah. As for emissions? Im from florida so... no emission laws haha
Edit: stock exhaust, you shouldnt hear or feel a difference. If anything, itll be raspier
Last edited by 95Maxed; 09-20-2011 at 04:42 PM.
09-21-2011, 06:49 AM
#8
if you gut your cats/pre cats or put in test pipes then your exhaust may get a bit raspy, it may not if you have a nice resonator in there. What it will almost always do is give your exhaust that popping noise as you decelerate. If you have a full exhaust the noise will be amplified and you WILL notice the backfiring.
Unless you are boosted/blown you wont notice a power difference. It will slightly free up the exhaust but not enough to notice without having F/I.
That being said, im happy i put a test pipe in, makes the car sound a little better I think hah. As for emissions? Im from florida so... no emission laws haha
Edit: stock exhaust, you shouldnt hear or feel a difference. If anything, itll be raspier
Unless you are boosted/blown you wont notice a power difference. It will slightly free up the exhaust but not enough to notice without having F/I.
That being said, im happy i put a test pipe in, makes the car sound a little better I think hah. As for emissions? Im from florida so... no emission laws haha
Edit: stock exhaust, you shouldnt hear or feel a difference. If anything, itll be raspier
Originally Posted by gatsugansu
did you notice power gains and mpg improvement?
09-21-2011, 06:52 AM
#9
I support your lack of support.
People keep using the word "rasp". I have to say, I'm getting a little tired of it. The whole thing is so-o subjective.
With gutted pre-cats, a cattman uneven y-pipe, OEM main cat, and cattman 2.5" cat-back, my exhaust sounds absolutely wonderful (to me). The tone is deep and consistently smooth. Much louder than stock (duh), but not at all like the continual drone of headers or a 3.0" setup.
Oops! There's another hackneyed phrase: "Drone". Sorry about that.
People keep using the word "rasp". I have to say, I'm getting a little tired of it. The whole thing is so-o subjective.
With gutted pre-cats, a cattman uneven y-pipe, OEM main cat, and cattman 2.5" cat-back, my exhaust sounds absolutely wonderful (to me). The tone is deep and consistently smooth. Much louder than stock (duh), but not at all like the continual drone of headers or a 3.0" setup.
Oops! There's another hackneyed phrase: "Drone". Sorry about that.
Last edited by Rochester; 09-21-2011 at 07:00 AM.
09-21-2011, 07:55 AM
#10
It is setlled then. I will gut both my precats, install the y-pipe and t-pipe. Hopefully I can get it done in one full day.
Got my cordless drill, chisels of various size, hammer. Wish me luck!
Got my cordless drill, chisels of various size, hammer. Wish me luck!
09-21-2011, 08:09 AM
#11
I've gutted my cats, 3" test pipe, and 3" exhaust with a 16" resonator...no rasping that I know of. Just that decelerating pop but it isn't loud enough to sound like a backfire pop.
09-21-2011, 12:43 PM
#12
Senior Member
Join Date: Jan 2010
Location: Denver, CO
Posts: 1,396
09-21-2011, 01:56 PM
#13
1.) Pre cats on both banks, vs 4th gen.
2.) We have proven that headers/gutted precats show a significant power increase on the 5.5 gen in NA form, reason being, refer to above.
3.) Sound is subjective, raspiness/drone, etc.
09-21-2011, 02:11 PM
#14
You might disagree. That's fine.
09-21-2011, 02:59 PM
#15
Senior Member
Join Date: Jan 2010
Location: Denver, CO
Posts: 1,396
Although very similar, the 4th gen is not the same as the 5.5 gen, most significantly in the pre cat area.
1.) Pre cats on both banks, vs 4th gen.
2.) We have proven that headers/gutted precats show a significant power increase on the 5.5 gen in NA form, reason being, refer to above.
3.) Sound is subjective, raspiness/drone, etc.
1.) Pre cats on both banks, vs 4th gen.
2.) We have proven that headers/gutted precats show a significant power increase on the 5.5 gen in NA form, reason being, refer to above.
3.) Sound is subjective, raspiness/drone, etc.
And yea the word rasp is very opinion based, i use that loosley
Rasp is an opinion oriented word yea. I agree with that hah
. maybe it's cali-spec. 
09-22-2011, 01:46 PM
#17
Now ya'll got me thinking maybe I should go ahead and invest in headers. Everythings gonna be off the car anyway, might as well get it done now. Any suggestions on headers?
preach
10-21-2011, 02:37 AM
#21
Senior Member
Join Date: Oct 2009
Posts: 1,432
im running all stock exhaust just with the muffler cut off and it sounds like a stock 350z i like it.
but after reading how much our stock y pipes slow us down i was thinkin about saving money and cutting the pre cats out and welding my own straight pipe to the cat. would they be worth doing?
but after reading how much our stock y pipes slow us down i was thinkin about saving money and cutting the pre cats out and welding my own straight pipe to the cat. would they be worth doing?
10-22-2011, 01:57 PM
#22
Join Date: Feb 2011
Location: Wasington Metro
Posts: 18
10-22-2011, 02:18 PM
#23
2 exhaust manifolds (duh)
2 pre-cats
1 y-pipe
1 main cat
Aftermarket y-pipes have a more free-flow design than OEM. Cattman's is an uneven length design.
Headers eliminate the precats, not an aftermarket y-pipe.
Last edited by Rochester; 10-22-2011 at 07:01 PM.
10-23-2011, 02:34 PM
#24
5th gen
5.5 gen
Last edited by IHAVEA2KMAXIMA; 10-23-2011 at 02:55 PM. Reason: More info
10-23-2011, 03:15 PM
#25
12-03-2011, 03:35 PM
#28
Finally got some time to tackle this job. Got the y-pipe off. 6 bolts off the manifolds came off easily. Man! Those 2 bolts on Catalytic converter are something else. Anyway here are some pics for comparison. I ended up cutting the bolts on cat. Now have to remove the back ones.
Cut with Dremel
My main cat looks to be intact. Since I'm putting in test pipe. Maybe sell it to junk yard
for the Platinum.
This is the reason, why I'm replacing y-pipe. gutting bank 2 cat and test pipe is just might as well do 'em while I'm down there.
P.S(for those of you live in the upper midwest or the salt belt like I do, Don't attempt this!! Unless you like swearing and grunting with rusted out crumbling bolts.
Cut with Dremel
My main cat looks to be intact. Since I'm putting in test pipe. Maybe sell it to junk yard
for the Platinum.This is the reason, why I'm replacing y-pipe. gutting bank 2 cat and test pipe is just might as well do 'em while I'm down there.
P.S(for those of you live in the upper midwest or the salt belt like I do, Don't attempt this!! Unless you like swearing and grunting with rusted out crumbling bolts.
Last edited by gatsugansu; 12-03-2011 at 03:53 PM.
12-04-2011, 12:56 AM
#31
12-04-2011, 05:11 PM
#34
Went for 20 min drive, no CEL light yet. Sounds real nice. Seems more power at high end but that might be my manifestation. I'll get sound clip if anyone interested and curious about gutted cat, y-pipe, and test pipe set up sound.
12-09-2011, 06:29 AM
#35
Junior Member
Join Date: Mar 2009
Posts: 45
Yeah i gutted out my firewall cat and i got the code but i am going to purchase the sim and get rid of it do you know if the 02 sensor can be reached from the top of the engine or the bottom of the engine
04-20-2014, 06:43 AM
#37
Just gonna throw it out... Been using 18mm spark plug non-foulers for quite a while with no codes.
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