I have looked around on here but i havent seen any answer on here for sure. Has anyone gutted the pre cats while leaving the exhaust headers attached to the motor. It seems if you remove the y pipe you have enough room to stick a long tool in there to tear out the cat components. Has anyone attempted this or am i just looking at it wrong.

 

Gutting cats?

What a terrible thing to do, leave them ***** cats alone!



Seriously tho, I'm sure it's possible but you'd probably break your damn back by the time you're done, plus it will not be the cleanest job in the world

 

I would think everyone....

Did you mean gut the cats without removing them from the headers?

 

HA. Good luck. Let me know when you get to all the nuts. And you do realize that the nuts are on top and that's the side the cats have to come out of?

 

Thats why I said you'd break your back doing it..Having to be bent down for a while in a doggy style position

 

I did see that lovely design with the bolts on the top side of the motor. And i would never gut those poor kitty cats. But bad old engine breaking cats i would. Ill need to look at them again but i thought i saw that you can remove the y pipe and get tools up into where the pre cats are. But then again, i havent gotten the greatest view.

 

Ok, so why cant the cats come out the other way.

 

To do this you need WD40,gator type 10mm socket, possibly a torch.
I have gutted precat+cattman Y pipe+ cattman exhaust catback (3inches).
You need to remove both exhaust manifold cover, depending on the condition of those 10 mm bolts, mine is badly rusted, soaked it first with WD4O, some we used torch to remove the bolt head. Once you remove it you can access the nut on top precat near the radiator and the nut of precat near the firewall. Remove the y pipe then remove completely the precats. The precat near the radiator is easy to gut but the precat near the firewall is a pain, took us 2 hours to gut it, start along the side not in the middle until the whole mesh collapses. Be careful those are asbestos.

Gutted precat give a lot of HP most especially if you have the same setup that I did.
Goodluck

 

I've gutted the rear (front falls out LOL) and it's no picnic.

By the time you've gone through all of the work you might as well have got some obx headers. They're pretty damn easy to bolt in.

and WD40 isn't a lube

 

Lucky you. Unfortunately, all this stuff is illegal (and practically impossible ) to do for all California members. Not sure about NY, might be the same ....

 

What's that? I can't hear you over the roaring fire of my big trash burning pit that may or may not include tires

 

If you're in Cali, you're screwed.

Otherwise, good to go lol

Another good idea is to get Ypipe (eliminates rear cat) and gut the front.. oh wait, you have 5.5gen, nevermind. No cat removal for you unless you get headers.

 

Well i live in iowa and no emissions checks for me. I guess i dont have the money to drop 900 bucks for cattman exhaust. In the reading ive been doing people have been saying the obx stuff is junk.

 

still better than stock manifolds

 

I've only had minor issues with my OBX headers.

Example - having to notch crossmember for them to fit. No big deal. Also, the flex sections are junk but any decent exhaust shop will weld in a new flex for you for cheap. Other than that they are good to go.

 

I gutted all 3 on my 02. take them all out and save the gaskets so you can find the right ones. I had a hell of a time finding the right exhaust gaskets for the cats at the parts stores.


once you have them out just toss the shields away but put the small bolts back in where the holes go all the way through.


main cat and front cat are easy. the one for the rear bank took hours, it will wear you out. I had to keep hammering my ball joint puller into the element and take out chunks at a time. it must be 5-6 inch thick element.


mine wasn't even bad I just didn't want to risk a clog in the future. it was the first thing I did when I got my maxima 2 years ago.


I'm still running stock exhaust so you cant tell I have gutted cats.

 

If you have any torque wrenches you should be set thats all you need to take off the cats

 

Like any aftermarket mods, you may or may not run into issues, whether you pay $900 or $300. Some of us had issues with Cattmans in the past, while some have not had issues with the OBXs, and vice versa, obviously. Over years of dealing with aftermarket stuff, trust me when I say you should never expect any job to go perfectly, especially as these cars get older.

 

Hows the noise level.

 

I'm running the stock exhaust so it doesn't seem to be any louder... maybe just a deeper tone at idle...

 

That's my experience, too. A tiny bit of throatiness, but almost unnoticeable. The stock muffler is ridiculous LOL.

 

one thing I noticed about the stock 02-03 mufflers is that that exhaust only flows out of one of the muffler outlets when at idle. I guess as more pressure builds up the other one opens up...

 

This one was discovered here long time ago. Thread is out there somewhere. And its not just 02-03 the 00-01 5th gens have it too

 

my max got quite a bit louder after i gutted the precats. sounds great

 

with factory exhaust ?


I made a quick video of my exhaust sound, totally stock with all 3 cats gutted, on a cold start 1,2000 rpm idle... https://www.youtube.com/watch?v=KWrn...ature=youtu.be




while driving you don't hear the exhaust at all..

 

with a megan racing catback

 

If i were to go to a shop, approximately how much would they charge to do the gutting? I went to one place and they told me $800.. I ran out of there.

 

they wont, it's illegal if you get caught gutting them. fine is like $10,000.


main cat and front cat is easy. the one on the rear bank is a pain. best bet is take that one to a good welding and fabrication shop. if your lucky they will cut it open, gut it and reweld it.

 

I've had it done in IL. Of course, IL doesn't give a **** about stupid federal laws.

 

FL either, out here anything goes and theres no car inspections. its common to see 1000+whp cars on the street out here...

 

If your gunna pay someone to do it, might as well get headers instead. they will want at least $300 to gut em. Took me all day to do mine. The most time consuming part is getting the material out of the rear bank cat.

 

Yeah that rear is a royal pain and will make your **** boil.

Unless you have ypipe and vq30
No rear cat with ypipe, I threw mine in trash can and felt very good doing it. Front was pretty easy to gut

 

If you do it yourself, wear a good respirator. That white flaky stuff? Asbestos.

 

its not asbesto's. I believe its ceramic with some titanium in it to handle the insane heat without melting. that's why lots of catalytic converters get stolen..

 

Titanium inside them is correct and why they're big money...
If you take cat guts to the scrap yard they will buy it. Not your neighbors cats guts guys. ..lol



We dont have any inspections in my state but the cops carry a meter to check if they suspect it during traffic stops. Yrs ago my freinds was checked on a 79 T-bird 351ci because it had duals and he passed. Had installed old gutted cats for looks...lol Long ago though and old hand meters..
I gut mine on my truck and gained 2mpg and more power.

I may be dead wrong here,
but Im throwing it out here as Ive wondered??



For those states that have inspections "can" you only gut the pre cats and leave the rear main cat intact and still pass emission inspection if no lights thrown?



The reason I wonder this is the perimeters must be lower than what these newer cars put out anyway? Does the state use a standard range and if so, its much lower because gas hog trucks/cars that had only one cat from late 90's on back must be able to still pass it, right?

If they dont have a set of perimeters they stay between in tests, then they would have to know every cars emission rating to know if its got all its cats? Is that correct?

Since we never had to deal with it Im only guessing but how would they know its true range on every car?

 

from what I remember. precats get hotter and work better than under car cats.

 

I thought it was platinum inside?

 

No

This ^^

Potentially yes. If they do a tailpipe test you 'might' pass as long as test is done with the main cat being warmed up enough. If they do the OBD II plug in test it is possible to have precats gutted and cel off. Just gotta hope they arent extremely thorough and find the precat material missing.

 

You're on point but the platinum that's inside is why older cars for say mid 80s into 90s foreign cars are worth much more. Sorry that wasn't a well constructed sentence. Anyway yea there are places that just specialize in extracting the precious metals out of cats. They slice them take guys out melt them down and remove the value.

 

In Pennsylvania, yes. I pass every year.