After researching some of the aftermarket headers for my 01 trans am I like the texas speed as it seems to be the most bang for the buck. Dont wanna spend the cash on the Kooks.

I want to have the headers go into my stock exhaust for low noise during regular driving and then an electronic cutout to go to maximum performance. Where would I put the cutout? I would assume I would need the Y pipe and then right after that. How much work does it take to put in the cutout? Do i need to pay someone to weld it in?

I would want to tune the car for the best performance after the headers install and I would do it with the cutout open. If I closed it during regular driving would it mess with the tune and have the car run unsafe?

I live in Illinois and they do emission testing here. I know they plug in something into the OBII sensor but I dont think they look under the car or hook up anything to the exhaust gases to see if there is too much pollution. I would like to put a high flow cat on it because honestly I dont need to pollute this earth for 1hp. Anyone from Illinois have a high flow cat that can confirm with that I would pass emissions?

TIA

 

Illinois OBD-2 Testing

I'm not familiar with Illinois testing policy. Please see the link. Tests may depend on where you live in the state.

 

DuPage county

 

Anyone?

 

If you run non emissions headers you'll probably fail if they open the hood. Those headers mean disconnecting the air pump and egr and that's an obvious thing to notice. If you run emissions headers you can keep the air pump and egr intact and have a chance of passing.
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For cats it's supposed to be an automatic fail if they're not the same style and in the same location as stock. Most mechanics don't know where the stock location is so it's more about the stock style. Stock is a 3 way system with post cat O2 sensors. If you run aftermarket cats you may need to print out the carb certification paper to show the inspector if they ask about them. It's really anyone's guess if you can pass with aftermarket cats since it's up to the inspector.

Basically if you live in a place that does emissions testing it's better to stick with cat back and not mess with the factory front half.

 

The emissions sticker on the inner fender doesn't even show the EGR, at least on my 2000. Maybe 99 and 98 have different stickers.

 

EGR was deleted in 2000. That's why the LS6 intake doesn't have an EGR port on it. Pre '00 the intake needs to be plugged when the EGR is removed.

 

Did they do away with the air pump at the same time? Sure would simplify things...

 

Technically, any emissions test center can open the hood to do a visual inspection if the tech wants too. Long tune headers with cats are an automatic fail by the book because the cat location changed. I have no idea how zealous the emissions test centers in Illinois are about popping the hood and looking. So basically, even if everything is set up otherwise perfect, the car can get failed for the LT's.

In some places, a certain amount of common sense gets used by places that do the OBD-2 emissions testing even if the hood gets popped and visual inspection occurs. Cars that pass the OBD-2 scan will get passed provided nothing flagrant is observed by the testing tech. This is a gray area.

Once upon a time, there might have been a heads & cam car with LT's that passed 15+ OBD-2 emissions tests over 15 years and never had a single issue passing the emissions testing
It's said ​techs eventually got nosey and popped the hood after putting the car on a lift to do a full visual inspection. The car got cranked and ran for 45 minutes because they were looking for a SES light to illuminate due to the LT's. They were stunned the car passed OBD-2 scans given the long tubes headers. The result said the car passed, the car had cats - so they passed it.

In theory if someone were to try this, this might have been the blueprint..or it might not, I don't know.

Long tube headers with the AIR check valves hooked up. There was a plate blocking the air check between the header and the air check valve. It wasn't noticeable.

All emissions devices were connected. ​​​​​A dummy coupling hooked the EGR tube to the top of the LS6 intake. The end of the EGR tune was cut flush so it bolted to the coupling and looked stock. The EGR could also be hooked to the aftermarket fast intake which is emission legal.

LS1 block, GM heads (ported of course) no aftermarket heads.

No bling in the engine compartment. Bling attractions attention. Aftermarket heads are bling.

Quiet exhaust. Very quiet. Like the SLP Dual /Dual catback quiet.

Discuss exactly what you are doing with your tuner. If the tuner turns off the emissions tests in the PCM the car will always fail despite not showing a SES light or code because the PCM can't complete the emission device test it runs. It takes about 600 miles of drive for the PCM to run all of the tests.

Get a good code scanner, check yourself to see if all the PCM's OBD-2 tests have been completed. Only take the car for the test when you already know for a fact the test status is PASS.

Cats in Y pipe are nice.

The car needs to burn clean, no smoke no stink, good tune.

The tune must set up to keep the front and rear O2 sensors active and the rear O2's need simms to emulate. O2 simms previously were made by Casper Electronics but the simms were ruled illegal and Casper stopped making them. They maybe available again from other sources.

Kook's LT's with Y pipe & green Cats would be my staring point. Kook's claimed at one point even with LT's their green Cats were super efficient and would light off so quickly that rear 02's could be installed and they would function normally. No 02 simms needed.

The car should have a near stock idle. No lumpy idle. 900 rpm idle can probably sneak by 1,200 rpm or lumpy less likely. Some techs won't care some will. The car has to be cammed to escape attention. For a LS1 224/224 114 LSA works well. This cam spec should pass a sniffer test in theory as well.

The cut out should go at the end of the Y pipe. This is roughly located under the rear passenger seat.

The tune should be done with the cut out closed. That's how the car will be driven most of the time. The slight change with the cut out open shouldn't be an issue.

​​​​​Typically, only 5-10 whp over a good cat-back on a 400-450whp set up.

 

^^^^^^ This is IT in one BIG nutshell! Let common sense prevail. Lend the appearance of all hooked up and legal. Idle REASONABLY smooth, even if at a slightly raised RPM. OBDII should show a clean bill of health.
If this were CA long tubes would be OUT, no questions asked. A nice stealth cam, no problem..
OR, have a pre-1975 car and all is good! BTW, ANY kit replicar can be registered in the year of the car being replicated! Such is California …..

 

Wrong, my 2000 had a LS1 intake and EGR. LS6 intake and non EGR was 01 and 02

 

Off a year. No biggie on this topic. You should figure out why your emissions sticker doesn't match your engine though.

 

Mine was an early model 2000 produced in 99.

 

If you have obd plug in only for the emissions test portion you will pass if your tuner tunes out the rear 02 sensors and the cat. Also works on EGR and air injection. If the inspector is thorough enough and actually looks at everything you'll fail the visual. Find a little tire shop or something does inspections, you'll likely find someone who doesn't care as much as at a larger facility.

Closing the cutout won't mess with the tune

The cutout needs to go in the I pipe or at the end of the I pipe

Texas speed and pacesetter make great headers for a low cost. Kooks are a waste of money IMO. They may make 2 more hp, but cost 1k dollars more. Speed engineering makes really nice headers for low money too. I have hooker headers and absolutely loved them but some people complain the coating comes off on the coated ones.

As far as pollution, you'd be amazed how much a well tuned car with no cats does on a sniffer. The safe tune will usually put out more hc's than the performance tune. I've tried it back to back on ASM inspection machines that use a probe in the tail pipe. I have had cars that passed with no cats and burned cleaner than they did before with the cat. So don't get too caught up in how much you're polluting with your late model hot rod.

Cut outs need to be welded in or have the pipe cut before and after and use clamps to install it. We don't know if you can do that or not so can't answer the should you have it welded in question. I would have someone weld it in though unless you can do it.

 

Had LT on from 2300 miles on 01 Z06 with high flow CATS, cam & tuned, never failed a Chicago test. Sons 2002 TA WS6 LTs never failed.