I do not have much cash to throw around, but do want to get a set of longtubes for my otherwise stock '02 Z06.

I would like to stay emmissions legal(texas) and still have the hp gain and improved sound that comes with headers, but on a budget.

On to my question: Would it be possible for me to buy a set of Texas Speed longtube headers(or similar) without the x-pipe, install them myself(I am a very competent mechanic), and simply take it to a good exhaust shop to have pipes made that will connect the headers to my factory exhaust?

I did this several times on my old-school muscle cars, but there were no electronics to mess with, etc. Is the factory exhaust in front of the TI cat-back just regular steel on these cars? How much power would I miss out on by not running the x-pipe? Can it be done?

Any help would be greatly appreciated. Thanks in advance.

 

The answer to your question is yes. The stock manifolds have a small section in front of the cats that goes up each side of the engine to mate with the manifold flange. What you would do is cut that off at the right point and weld a flange or fitting there that would mate to the collector of the header. Then you'd have the stock cats in the original placement. The factory exhaust is just regular steel up front. I don't think you'd be missing much by running the oem 'h-pipe', but the cats are restrictive and you would see some power from installing high flow cats.

I know Stainless Works makes these 'adapter' fittings to go between the stock exhaust and their headers.

As far as it being legal in Texas I wouldn't know the answer to that. You'd have to check your laws on that there.

 

SLP also makes emissions legal headers, but i've heard they are a pita to install.

 

Emmissions isn't a problem if I can do this. The goal is to have headers and use the factory exhaust, including factory cats. As long as I still have cats I will be legal.

The way I figure it I can get a set of headers from texas speed for $500, install them myself, and pay only a few bucks at an exhaust shop to make a small flanged pipe to connect my factory exhaust to the headers. I could theoretically have headers for under $600.

Would this kind of setup cause the computer to throw any codes I will have to get removed? I probably won't be able to afford a proper tune for a while. The tune would cost about the same as the headers .

 

Well, hope you have a good muffler shop to do it cheap, it was easier for me to save $$ and get a system, Tried it, the LG LTs didn't come close and I need cats, it would have been a major PIA to make it work, just saved an bought the x-pipe... but different circumstances...

Anyway, there are two sets of O2 sensors. Most LT headers move the fronts further back, so the stock ones won't fit any more. Most people use the rear O2s to reach the new locations, but that requres either new O2s or a tune to remove it the code for the rear. The good news is that the rear O2s don't really impact anything and you will get a check engine light but it will not effect the performance. What will effect the performance is if you melt the front O2 wires, so be careful on how your route them.

I would ask texas speed if their headers could mate up to the stock H-pipe. You may not be able to use the stock cats, which will make it stink. Each LT has different dimensions, not a lot really care if they mate up to the stock H pipe because they want to sell you more stuff.

Using a systems x-pipe is more about sound and ease of install, HP is only 1-2 maybe 3.

Maybe look at the e-bay ehaders, seemed a few liked them they just took more effort to work...

For your price range I would suggest doing a CAI instead. I think most do that as a first mod, and they don't have a lot of hidden costs... Vararam is popular.

Good Luck!

 

not sure about emissions, but to have a good shop make the X...yes. coudl prob just chop up your factory H pipe and save more money.

 

I JUST WENT THROUGH THIS TODAY, The stock cats are going to be VERY difficult to get back under neath the car with the added length of the tubes, also if your car has pre-cats...I think it would be even more tough.
I'm not saying that it's impossible but you'd probably be better off selling your stock cats and buying some after market cats just for fitment issues if nothing else. The reason I say you'd be better off that way is because depending on which headers you have, you may have to cut off so much of the collector that you'll have to weld on new bungs for the front 02's.
There's just not much room to work with for the big stock cats under these cars.
DZ

 

I would suggest taking some measurements and make sure you have the room to fit the stock cats where they will end up. The reason for O2 extenstions with LT's is that the cats are moved back a considerable distance. Here is a compare with LG Lts and stock system.

 

I would think that it wouldn't be possible, especially after looking at the pic that "Torch Red" just posted. If you were insistent on keeping the "pre-cats" to remain smog legal, I'd go with "shorties", and save yourself a LOT of hassle

 

I'd stick with the manifolds and save the $$ on shorties. You won't see any appreciable gain. Unless you simply want something that looks nice.

 

Anytime you change the position of the cats, it is no longer legal.

That's why all long tubes do not have a CARB number. Only shorties. If you absolutely have to have headers to bolt up to stock pipes, shorties are the way to go. Performance, however, is not quite long-tubes.

I wouldn't re-use the stock cats, since they are pretty restrictive. You can get high-flows metal-matrix style for pretty cheap.

If you really want to go cheap, get a full pasesetter system, cut the x-pipe and add your cats.

Why not look into those OBX headers? Plenty of threads here on those.

As for codes, no question about it, you will get P0420 and P0430. Anytime you move the cats your going to get 'em.

 

If the headers have to flow through stock cats and a stock catback then your just wasting your money on the headers. Headers can't flow any better than the components down stream. I ran Lts with stock cats, x-pipe and a corsa exhaust for about 4 months - car didn't really feel that different but it sounded better. Then I switched to hi flow cats. The increase in power was very noticable.

You would be better off changing to a more free flowing cat back than adding headers to a stock exhaust system.

 

Completely agree. Shorty's are also the only type of header that will allow you to use your factory cats. Save up for long tube headers and aftermarket high flow cats, otherwise you're kinda wasting your money.

 

Please try to speak for your state, but not for everyone.

There is no "visual" under the car for late model Vettes (and most other vehicles) in Texas and only a cursory one under the hood. It gets plugged into the emissions testing machine through the ALDL port and as long as there are no MIL Readiness malfunctions or other disqualifying codes, your good from an emissions standpoint. The testing is done on rollers both at idle and at speed.

I've had my '99 inspected (including just a couple weeks ago) every year here and not ONCE did anyone ever look underneath for the cats' position or location.

 

I think the SLP or the Bassani are about the only LT headers that can use the stock cats and H-pipe. The SLP pipes are contorted all over the place, and require several feet of heat-resistant tubing to protect all the things they come close to. The Bassani, per an article I read in Corvette Fever, are short enough to just mate to the front of the cats.
You cut the pipe off right at the cats, roll a flange on the pipe, and the Bassani header mates up to the flange. Of course, these headers cost about $1200 I think. They did get about 40 HP (?????) with a tune and the stock cats though (if you believe everything you read in the mags).

One good thing; there is a market for the Z midpipe. The guys with the
'01-'04 4-cat systems will pick them up to get rid of the front pre-cats.

DG

 

Where is the proof that our stock cars are THAT restrictive?
1-2hp is not a big deal.

 

The collectors on Kooks LTs terminate just in front of the stock main cats. They sell a connecting flange that can be welded in just in front of the cats that hooks up to the collectors. I did it.



The length of the stock mid section and H-pipe remains the same and the cats do not move.