Emissions question

tehnick · Jan 4, 2007

Kinda curious about emissions and legalities of different setups. Been putting together some pricing and other options for some exhaust and really like the idea of going full SLP from the headers out. Such as long tubes, catted x, and LM II's. Been reading lots of websites that say that LT headers are not legal for emissions, but I was under the assumption that they should be fine as long as you have cats in place.

If anything, I can imagine that the setup will be loud as hell. What are some exhaust systems that sound good? Looking for more of a low end growl with no rasp but still emissions legal. I am pretty set on either LM II's or Stingers for the cat back, but what about headers and mid pipe?

Organizing a list of some things to do so I can start working out a budget and figured exhaust would be a good place to start.

wythors · Jan 4, 2007

In WA a 96 and later car does not have to pass a sniffer test. They plug into the OBD port and, as long as there are no codes set, you pass, even with an off-road pipe. After that other thread about noise compliance in OR, I can tell you from the intimate personal experience of owning two Loudmouth-equipped cars, you're going to have a problem there.

tehnick · Jan 4, 2007

wythors said:
In WA a 96 and later car does not have to pass a sniffer test. They plug into the OBD port and, as long as there are no codes set, you pass, even with an off-road pipe. After that other thread about noise compliance in OR, I can tell you from the intimate personal experience of owning two Loudmouth-equipped cars, you're going to have a problem there.

IIRC, stock GT exhaust is 2.25" and the LM II's are 2.5" correct? I was thinking that with the simplicity of the way the LM II's are designed that you could also just bolt up some different mufflers to mellow the sound temporarily since it's a clamp system. Since you have to run a car through every couple years it shouldn't be too much of a hassle to bolt on some different compatible mufflers to mellow the sound enough to pass the audible test. I recall that when I bought this car all they did was plug it in and check the ODB and sent me along with a pass. Even then, it's easy to just disable the sensors from reporting any codes with a flash defeating the purpose of plugging in. Rock on.

YardSpecial · Jan 4, 2007

The ONLY reason long tubes are ilegal is the fact it moves the factory cats from there orginal loctaions.

No cat can be replaced, unless proven bad by a repair shop.

We are all siners on that one if you ask me. What is really stupid is the fact is its ilegal to put cats on say a 78 truck............what is wrong with that ???

Stupid bean counters and ghey laws !

tehnick · Jan 4, 2007

YardSpecial said:
The ONLY reason long tubes are ilegal is the fact it moves the factory cats from there orginal loctaions.

No cat can be replaced, unless proven bad by a repair shop.

We are all siners on that one if you ask me. What is really stupid is the fact is its ilegal to put cats on say a 78 truck............what is wrong with that ???

Stupid bean counters and ghey laws !

I would think with longtubes that have cats in place that it shouldn't matter only because the exhaust will pass through them either way. The only difference is that the fumes pass through more tubing before going through the cats, as opposed to going through the cats sooner. To me, I don't see how that should create a problem unless having the cats further back causes them to be less effective.

WaterPog · Jan 4, 2007

In Oregon you should at least have a cat shell under the car, even with ODBII because they will often check with a mirror to make sure they are there. Other than that and the noise issue everything can be fixed in the chip to get it to pass the actual "emmisions test".

tehnick · Jan 4, 2007

WaterPog said:
In Oregon you should at least have a cat shell under the car, even with ODBII because they will often check with a mirror to make sure they are there. Other than that and the noise issue everything can be fixed in the chip to get it to pass the actual "emmisions test".

Rock on man, thanks. So, in your opinion would the SLP be the way to go in terms of the ease of swapping mufflers and sound quality? I don't think I have ever heard full SLP with LT's, catted X, and cat back. I have mainly just heard catback with stock headers and mid pipe. I know that SLP has high build quality but would that combo sound mean as hell?

352Ford2 · Jan 4, 2007

YardSpecial said:
The ONLY reason long tubes are ilegal is the fact it moves the factory cats from there orginal loctaions.
QUOTE]

Thats only true in californa and that is the whole reason "shorty" headers exist. It's not for performance reasons.

it depends on the cat, but they need heat to "light off" the catalist, so that is what those two "preheater" cats are doing so close to the engine on our cars. So a really general rule of thumb is the longer it takes to heat up the cat, the more cold start emmsions you will have.

It is far more complcated than this, but this is a good general gist.

yello05 · Jan 4, 2007

You are not allowed to TOUCH original factory cats unless they go bad. Period, end of story. It IS illegal to alter/remove/replace working cats. Not to say that it isnt done everywhere and by anyone, but it IS illegal. Ask your favorite muffler shop if they have any friends that have been busted and I guarantee they have.

The long and short of it is that around here they dont care- oregon does often use a mirror to look but I have never seen washington even glance. As long as oregon see's cats they dont seem to care about them- they arent going to look for a c.a.r.b. number or anything like cali does.

wythors · Jan 4, 2007

tehnick said:
Rock on man, thanks. So, in your opinion would the SLP be the way to go in terms of the ease of swapping mufflers and sound quality? I don't think I have ever heard full SLP with LT's, catted X, and cat back. I have mainly just heard catback with stock headers and mid pipe. I know that SLP has high build quality but would that combo sound mean as hell?

I've got FRPP shorties, a Bassani catted-X and LM 1 on my 5.0. "Mean as hell" is a pretty good way to describe it. It's significantly nastier than the SLP with stock H on my wife's 96 Cobra. How much of that is pushrod vs. dohc, I don't know, but mine is a lot more aggressive sounding.

On a side note, I have considered getting a set of SLP Flowpath mufflers and seeing how they sound for something different. They're 'glass packed, so they should be significantly quieter.

hyper00 · Jan 7, 2007

I don't want to hijack tehnick's thread, but I am also shopping for a full exhaust. What cat-back do you guys like the most for sound.

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