I know there are a couple threads on this, but just wanted to get a new update. Why is it not common for people to gut their OEM cats? Does it not add any hp? Does it sound terrible? Anyone w/ experience or thoughts on this lemme know thanks!

 

I'll venture a guess: it's a PITA and test pipes aren't that expensive. Those stock cats are also very expensive, so good to hand onto them if you need to return to stock to sell or get inspected.

 

I have gutted Random Tech high flow cats, amazing. Find someone who had theirs collapsed and buy em.

 

gutted cats will give you the same sound as test pipes. So you might as well go with pipes if your planning on gutting out cats. You'll save on labor and heath risk

 

how do you gut them?

 

long metal rod does the trick

 

+1. I had an extra set so I went ahead and gutted them because it was essentially a free mod. It was a PITA but they sound awesome, better than non-resonated test pipes IMO. They still are heavier and have more restriction than test pipes. Test pipes are one of the cheapest mods out there, I would just pick up a set and keep your stock cats around for inspection/emissions testing.

 

Maybe gutted stock cats won't crack as easily as test pipes. It would be a good idea.

 

1nate7, did you gut both the primaries and secondaries? I want better air flow, but dont want my car to be super loud. I have a custom made exhaust, so it's already pretty loud. HFCs are expensive, so i was just thinking of going the gutted cat route then changing them out down the line. But will they make a noticeable hp difference or is it not worth the time/money?

 

One plus to gutted cats is in Cali, if you're pulled over, you can visually pass an inspection by the police...they have a mobile emissions team up in Nor Cal, and they monitor cars as they drive by - if they see your emissions are too high, they'll pull you over. You can say that the car had been running rich for awhile and must have damaged the cats (excess fuel into your cats will eventually degrade the interior)

 

I gutted both. I did it mainly for the sound because I am still on the stock exhaust. I wouldn't say it was a huge gain, but the combination of gutted cats/intake picked up 2 mph in my trap speed. I would estimate the sound level increase to be somewhere in between test pipes and high flow cats.

 

I just got done installing and gutting my oem cats. i can say it's a PITA but if you have a heavy duty drill (24v at least) and an extension rod it's not so bad. about 3 hours for a pair working non-stop. A buddy makes it 2x as easy. The quality is great (since its OEM) and prolly will never break. Sound is very nice and throaty with VERY little rasp. No change in exhaust note until about 3000rpm and above. No CEL and of course no fitment issues.

 

I am considering doing this to my stock cats but I am not sure If I want to because I love the sound of the stock Z. I may just have some cutouts welded on.

 

I've got my cats gutted. Sounds very good and doesn't make it a whole lot louder.

If you like the "Z" sound... don't do cutouts! Go unbolt your exhaust after the y-pipe and drive around, then come back and decide if you want cutouts.

 

idunno, this still doesn't really seem like its worth. I mean after all was said and done with my HFC's the biggest change to me was the amount of weight I saved. the stock cats must weigh 15-20lbs each vs the HFC's were like 5-10lbs and I would imagine test pipes must weigh less.

 

They work well... found some cheap on ebay that were half-way gutted and it still took some time completly gut.

Sounds good with the borla TD.

 

No they don't...they are not as loud and raspy sounding. They sound like stock at idle and are not much louder than stock at full throttle.

 

Should notice more of a difference if you have headers.

 

i gutted my secondary's a year ago, good mod

see here:

www.my350z.com/forum/showthread.php?t=125238