DanMan35

I live in Nevada. My Z06 is stock except an intake and I want to get long tube headers and an exhaust.

My question is I know usually you can get headers with high flow cats or with no cats at all. I would imagine no cats would provide more power but would probably not pass emissions testing.

So for all you guys who live in stricter areas like California, Nevada, etc...how do you get your car smogged without cats?

SuperchargedTundra

In NY your allowed 1 "not ready" so you just tune out the O2 sensor and your set. I have cats on my Z though.

jb78L-82

I know in my state with emissions testing, my builder who did the bottom end of my 78 L-82 C3 and mostly mods current C6/C7's, when he installs LTH, Exhaust, etc on C6Z06's like my 2010 Z, he just goes into the ECM and turns off the "check engine" function for exhaust with no cats. When the car goes for emissions, when the tester plugs into the ECM, there are no codes indicating anything is amiss...no issues but you need to have an ECM adjustment after the change. I personally would just run high flow cats since the difference in HP is VERY small versus a catted exhaust.

atljar

Its amazing how far a few bucks to the tester could go....

psp6158

FlipRay

If you have emissions in your state, why would you even wanna go catless? Sure you can trick the computer but you wont be tricking the sniffer.

nuke61

You first need to find out if Nevada does an emissions check using just the ODBII connection, or if they also do a roller test. If it's a roller test, you won't pass without cats. If it's just the computer, that can be tuned out using HPTuners - probably others too but I only have experience with HPTuners.

DanMan35

I copied this right from the Nevada DMV website:

Types of Tests
Nevada uses On-Board Diagnostics (OBDII) Testing for 1996 and newer vehicles. The operator will connect an analyzer to the OBD computer in your vehicle. Data from your vehicle will indicate whether its emissions systems are operating properly and within emissions limits.
Older vehicles are tested with a Two-Speed Idle Test. The operator will test your vehicle once at idle speed, then test it again with the engine running at approximately 2500 rpm. Older diesel vehicles are tested on a dynamometer.

So it looks like it is just OBD testing

meanjoe

From what I've read the cat delete cars are kind of smelly, exhaust smells bad. Never experienced it though. Can anyone verify that?

Mike's LS3

sniffer as in nose, the inspector should be able to detect the smell. Sniffer as in emission testing, in CA they do not use them anymore, just hook up to OBDII for readiness codes and do their visual inspection at their discretion.

Tech

It's definitely true.

nuke61

To the OP, I agree with the others who say keep the cats. However, if you're determined to get rid of them, any tuning shop should be able to set the 'ready' code for emissions and/or disable the 'check engine' code.

DanMan35

Anyone have test results on a dyno of the difference between long tube headers with no cats and with high-flow cats? Is the difference very small? If it is then I'd probably go with the cats, although it looks like I would have to pay about $300 more for a catted pipe as opposed to a catless pipe so that kind of sucks.

Tech

I think the most I've seen on a stock-ish car was 8 rwhp. You won't feel the difference. You'll hear it though.

DanMan35

I'm torn. If Nevada only does OBD testing and no other tests then I believe I would still pass emissions with no cats. No cats provide a bit more power and they are cheaper. But then I don't want my car smelling like exhaust fumes every time I drive it or for me to get out of my car smelling like exhaust, but then I don't necessarily want to pay $300 extra to get high flow cats lol. Is the smell from no cats bad?

Tech

Smell isn't that bad on a stock cam'd car. My fiance doesn't mind it at all.

SuperchargedTundra

My daily is a Fiesta ST with no cat, I dont think it smells bad at all.

nuke61

Find a car club that has a lot of cars from the 60s and 70s that have the original motor that hasn't been replaced with an LS or other modern setup. They likely won't have cats, because they never came with them. I don't think it smells bad at all, but I grew up with those old cars. Then you can decide for yourself if you'd have a problem with the smell.

Macattack

I agree, the smell isn't really an issue for me. I really didn't notice it until I read the threads on cat vs no cat. I'd probably go with the catted pipe if I had to do it over, quiet down the exhaust a bit and I do think the exhaust note is a little more raspier with the off road pipes.

pjazz

You need to not only think about what you can tolerate but the people around you also. I can smell a car without cats when driving behind them . Give the environment a break.