Gutted my cats. What a difference for the price of an O2 sensor socket ($10.40). Nice increase in throttle response and no CELs yet. Oh so stealth and the service manager will never know. Hehehe. I have a pic if someone wants to host it.

 

noticibly louder? where if anywhere do you feel an increase? how long did the job take..
thanks

 

i can host

my350z@***.net

 

sweet idea!
i did that with my ol 88 5.0 rustang a long time ago
it was one the best bang for the buck mod evAr - and was worth an instant .25 quicker 1/4 easy
can ya make a quick faq if possible cause the Z is a whole different beast when it comes to CELs an stuff
tia!

 

This is what i have been thinking about doing, i dont see the need to buy pipes when you can just gut the cats. People use to do this on the 90+ 300zx's. Cant wait to see the pics.

Later
Aceman

 

cool man. post some sounds if you can.

I went with buying pipes because A) inspection, just in case B) in case something happens and i have to sell the car.

I also think the test pipes were a little wider diameter. I didn't measure though. I can measure the stock pipes tonight. Can anyone who has the test pipes not installed yet measure theirs?

 

It is louder, but in a good way; IMHO. The increase is everywhere but particularly noticible in the high end of the tach. I am hoping that in lieu of not having tube headers, the gutted cat acts as a collector rather than just a consistant diameter test pipe. I used this theory successfully on a 944 TSwhen I went from Bursch test pipe to gutted factory cat years ago. It was about a 5 hour job. The pre-cat sensor area is just honeycomb and insulation matieral. The post sensor area is pretty tough. It is like tightly woven metal foil. I had to knock the whole element out of place and nibble it away through the rear oriface using plumber's pliers. Worth the DIY effort by far. My only other mod is a panel K&N; not because it flows more than the stock paper ('cause it probably doesn't), but because of a theoretically probable enhanced pressure drop scenario that could assist throttle response.

 

Test pipes may be a little wider, but they don't allow for more collector area like the stock gutted cats. With headers, the test pipes are probably much better; but with the cheesy stock exhaust manifolds, a collector may be beneficial. I am relaying on bribery to pass emissions. Test pipes are definitely the overall better alternative.

 

Hi all,

I may be thinking about doing the same but does anyone has any figures on gains from punching through the stock Nissan cats?

Since we have 2 cats on each pipe, how about gutting either one of it before or after the sensor. Will we see any gains while being "not as illegal" has gutting the entire thing?

Or I may be well better off paying for a set of test pipes?

All this asumming that I will still be on stock headers for a while.

Cheers!

 

gains will be about the same as putting on test pipes....

only bad thing.. come emssions testing time.. your screwed...

if you wanna get rid of that material in the cat.. take the metal handle off of a bucket.. you know the industrail construction buckets.. it has a little HOOK on it.. bend that so it is a right angle 90degrees ya know.. and scrape away...

i have heard of people putting that on a power drill and just turning it on and letting it rip away...

besure to do that OFF of the car...

 

Hey Thanks, I guess there are ways to get around the emission test (at least from where I am).

 

3KGTO

The secondary cats would be the ones to get rid of because all they do is "clean up" behind the primary cats according to my friend who is a nissan mechanic. He actually suggested that I do away with the seconday ones to see if there would be a difference. Another mechanic said that the Z cats are already high-flow and taking them off would not result in much, if any, gain. I do partially believe this due to the CrawfordZ high-flow units only producing 3-5 hp. Clean em out dude, go for it.
I'm goin with the test pipes though so I "could" go back stock if needed. Buying new converters is EXPENSIVE.

 

Having seen what is in the cats and the effort it took to dig it all out, it is hard to imagine that adding slightly higher ID piping via an aftermarket exhaust system would yield better exhaust gas flow than a gutted cat. The gutted stock cats (pre/post) also have a much higher ID than cat pipes. It turns them into reflective resonators for great flow. I don't know many Nissan mechanics that have actual experience with gutted cats, so their opinions may be useless regarding this issue. FYI, pre is before the O2 sensor bung highlighted by crowbar#1 and the post is highlighted by crowbar #2.

 

Thanks for all the input.

 

I have heard that our cars will pass the emission test without the cats, the only problem would then be the visual test. So we should be able to get away with it? What do you think?

 

in NY that might be true, I have no idea. Emissions tests vary from state to state. In CA, no way.

 

Why did you say this: "for the price of an O2 sensor socket ($10.40). "
Since these are stock, why would you need a socket???

 

I believe he's referring to a socket to remove the 22mm hex fitting on the O2 sensor itself.

 

ahhhhh, gotcha.
thanks.

 

Z monster or anyone,

I am hopefully going to gut my stock cats next weekend.....other than Z monster, has anyone else done this yet.........any Check engine lights yet.........Monster said he hadn't had any, but the original post was 2 months ago.........anyone having any problems at all.................
Thanks!

I'm not really mechanically inclined, but I'm learning!