Tried to hollow out Precat = FAIL

[Derrick2k2SE]

Headers will increase the volume but the sound is pretty good. There's something about having exhaust travel through a short, fat, hollow section of pipe then back into a smaller pipe that just sounds bad.

It's true that 4 and 6 cylinder engines have a different sound. In this case though you have to look at it like two 3 cylinder engines each running with gutted cats.

I have to say I've never heard a Max run with gutted precats. From previous experience and in theory I don't think it will sound good at all but who knows until someone does it.

If it sounds really bad you could pull them back off and take them to an exhaust shop. They could cut the flanges off and weld in some 2 inch pipe. They might even be able to run a pipe through the hollowed out section and weld it at the flange without cutting anything. Basicaly, they'd be using the stock flanges to make test pipes. Since they'd be off the car they could do it without breaking the law and risking a big fine for removing them. That would help with the sound without loosing any power gain there might be.

[Child_uv_KoRn]

And I thought ford made bad headers lol. That one is horrible.

[e-subliminal-2]

trust me from being in first hand guttted max. Sound was AWESOME. deap but not toooo loud, i'm not sure if Ahmad_1290 still has his f/s section under member rides but he had some vids up of his. IMO it sounded pretty bad ***.

[e-subliminal-2]

maximas for sale* He had some vids up of his car.
judge for yourself.

[Ahmad_1290]

^^not anymore. I just recently changed out my rear section. I'll post vids up soon.

[Derrick2k2SE]

Originally Posted by e-subliminal-2

trust me from being in first hand guttted max. Sound was AWESOME. deap but not toooo loud, i'm not sure if Ahmad_1290 still has his f/s section under member rides but he had some vids up of his. IMO it sounded pretty bad ***.

Cool, did you notice any power gains? Also, was this with the stock Y-pipe?

[E55AMG2]

Originally Posted by Derrick2k2SE

Headers will increase the volume but the sound is pretty good. There's something about having exhaust travel through a short, fat, hollow section of pipe then back into a smaller pipe that just sounds bad.

It's true that 4 and 6 cylinder engines have a different sound. In this case though you have to look at it like two 3 cylinder engines each running with gutted cats.

I have to say I've never heard a Max run with gutted precats. From previous experience and in theory I don't think it will sound good at all but who knows until someone does it.

If it sounds really bad you could pull them back off and take them to an exhaust shop. They could cut the flanges off and weld in some 2 inch pipe. They might even be able to run a pipe through the hollowed out section and weld it at the flange without cutting anything. Basicaly, they'd be using the stock flanges to make test pipes. Since they'd be off the car they could do it without breaking the law and risking a big fine for removing them. That would help with the sound without loosing any power gain there might be.

If the rest of the exhaust is stock, the volume change will be minimal. With an aftermarket B pipe/muffler the volume change will be dramatic.

Gutting the precats is not going to really change the sound dramatically...perhaps a bit more rasp, but thats about it.

[e-subliminal-2]

Originally Posted by E55AMG2

If the rest of the exhaust is stock, the volume change will be minimal. With an aftermarket B pipe/muffler the volume change will be dramatic.

Gutting the precats is not going to really change the sound dramatically...perhaps a bit more rasp, but thats about it.

IMO, it DID change the sound DRAMATICALLY.

It wasn't my car, ask Ahmad_1290 for vids, perhaps he could post one up here of his. He recently got exhaust so obvciously thats not just gutted cats, but he has a few vids of it before hand.

[E55AMG2]

Originally Posted by e-subliminal-2

IMO, it DID change the sound DRAMATICALLY.

It wasn't my car, ask Ahmad_1290 for vids, perhaps he could post one up here of his. He recently got exhaust so obvciously thats not just gutted cats, but he has a few vids of it before hand.

I didnt notice much change when I did it to mine. It was raspier, but not much louder. Then again...if your precats are plugged up badly it might make a big difference, however mine were not. Once I swapped in a Y and B + Magnaflow, the volume/sound did change dramatically. Then I swapped the Y for HS Headers and the car was obnoxiously loud.

[Grand_hustle17]

if i could do this myself i would end the "does it make power" questions, ppl on here has it done but dont really post track nor dyno numbers... maybe it really doesnt do anything and ppl get crappy numbers and is just too embarrased to even tell... im losing interest in this thread daily... how a car feels after any mod is so insufficient and can be just all in the mind, my car felt great with an intake on it but does that means i made any power???... until someone can prove a difference and show some kind of evidence then this thread is worthless... srry if anyone is offended... why not just prove to maxima.org if this is really worth it???????????

[E55AMG2]

Originally Posted by Grand_hustle17

if i could do this myself i would end the "does it make power" questions, ppl on here has it done but dont really post track nor dyno numbers... maybe it really doesnt do anything and ppl get crappy numbers and is just too embarrased to even tell... im losing interest in this thread daily... how a car feels after any mod is so insufficient and can be just all in the mind, my car felt great with an intake on it but does that means i made any power???... until someone can prove a difference and show some kind of evidence then this thread is worthless... srry if anyone is offended... why not just prove to maxima.org if this is really worth it???????????

Does it make power, No.

Why: it makes a big chamber in the exhaust for the gasses to cool and slow down. This gets rid of the scavenging effect that aids in making HP, and decreases the VE that would help make torque

If you want the car to make a bit more noise, there are easier and cheaper ways that actually add HP. Gutting honeycomb style cats has never made power...the pellet style (ie old GM cats) it makes a big difference.

[Grand_hustle17]

Originally Posted by E55AMG2

Does it make power, No.

Why: it makes a big chamber in the exhaust for the gasses to cool and slow down. This gets rid of the scavenging effect that aids in making HP, and decreases the VE that would help make torque

If you want the car to make a bit more noise, there are easier and cheaper ways that actually add HP. Gutting honeycomb style cats has never made power...the pellet style (ie old GM cats) it makes a big difference.

i agree... i dont get why would somebody go through the hassle, why not just gut the catalytic convertor befor the B-pipe, makes for a good sound also

[E55AMG2]

Originally Posted by Grand_hustle17

i agree... i dont get why would somebody go through the hassle, why not just gut the catalytic convertor befor the B-pipe, makes for a good sound also

Why not just remove them altogether and make power?

[Grand_hustle17]

Originally Posted by E55AMG2

Why not just remove them altogether and make power?

cause im now confused... so are you saying it would be better to just remove the cats in the headers???... how???

[crazy97]

Originally Posted by Grand_hustle17

i agree... i dont get why would somebody go through the hassle, why not just gut the catalytic convertor befor the B-pipe, makes for a good sound also

You do this to save your engine from the precat dust from being sucked back into the motor and causing oil cunsumption or worse..

Saved the I35 motor from immenent oil consumption......

[Grand_hustle17]

Originally Posted by crazy97

You do this to save your engine from the precat dust from being sucked back into the motor and causing oil cunsumption or worse..

Saved the I35 motor from immenent oil consumption......

i thought a vehicle's exhaust system only exhale not inhale, so how would gutted headers or cat convertor suck dust in the motor???

[crazy97]

Originally Posted by Grand_hustle17

i thought a vehicle's exhaust system only exhale not inhale, so how would gutted headers or cat convertor suck dust in the motor???

I dont know, but they had a LOT of problems with the Altima 2.5's. I googled-- precat failure engine oil... and got nothing but Altima links with plenty of complaints/horror stories from owners. I think the 3.5 is in the same boat to a lesser degree though.

[e-subliminal-2]

Well this thread wasn't to debate the hp gains of gutting it, It was because he had a problem gutting his for whatever reason he decided on doing so. People I know do it just because they're cats are shot and don't feel like buying a new one when they're planning on buying headers pretty soon or down the line. But that's just me. As for dyno numbers, i'd LOVE to see someone accumulate some, until then I guess it's just gonna be a debatable topic someone will probably bring back up in about a week or so on here..

[wish2345]

i think my precats are crapping out on me that is why i tried and will hollow them . not doing it for any other reasons. I dont care about HP gains.

[CMax03]

Separate it from the exhaust manifold and the ypipe and beat it out, might wanna wear a dusk mask seriously!

[Grand_hustle17]

Originally Posted by crazy97

I dont know, but they had a LOT of problems with the Altima 2.5's. I googled-- precat failure engine oil... and got nothing but Altima links with plenty of complaints/horror stories from owners. I think the 3.5 is in the same boat to a lesser degree though.

i guess... could it possibly be coming from somewhere else but most just blame the headers??? just sayin

[Blitzfist]

I just gutted mine today and I am very pleased with the sound. Its deeper sounding, however its not all that much louder. You can barely notice a difference from inside the car. When the car idles it has a really nice tone to it but isnt obnoxiously loud. If you guys want I can post a clip

[boost4age]

please do post a clip and a video if possible

[boost4age]

Originally Posted by Blitzfist

I just gutted mine today and I am very pleased with the sound. Its deeper sounding, however its not all that much louder. You can barely notice a difference from inside the car. When the car idles it has a really nice tone to it but isnt obnoxiously loud. If you guys want I can post a clip

have u had the check engine light come on at all? i was told it was a sensor in there i was thinking about doing mine because the materials inside of it are lose....

[Ahmad_1290]

Originally Posted by boost4age

have u had the check engine light come on at all? i was told it was a sensor in there i was thinking about doing mine because the materials inside of it are lose....

If you get a o2 sim or use anti-foulers you'll be fine. I used anti-foulers and no CEL

[E407 Jae t]

so does anyone recommend taking out the cats? does it push more?

[boost4age]

ok cool. im gonna give it try