are they coated from the shop? Have they got the air pipe thing?
what kind of y-pipe did you use?
And will they work with the stock mufflers, or will the stock mufflers hold back flow to much?

And if you got pictures of hooker headers installation, please show me :)

thanks

 

Coating is an option on all headers.
usually they have the AIR and O2 provisions on them.Once again you haev to order the part# with that on them.
Don't hookers come with a standard 'Y' pipe in the set??
Yes, your stock mufflers are a restriction I'd change quickly.

 

I've heard the O2 sensor is in the #7 primary tube. Some people like to move it to the collector. I've heard you can not weld after headers are ceramic coated. You may want to check into that before you order coated headers.

Depending on regulations, I would not use a Y-pipe. I would use a mandrel bent, 3" dual exhaust with (2) 3-way hi-flow cats, an X-pipe and mufflers that sound good, if you are going with a mini/stealth ram intake. The 3" dual exhaust I described is very similar to the system SLP used to sell, I added the cats and replaced their center resonator with an X-pipe. I don't know what brand mufflers they used, so I would choose by sound and looks.

Aftermarket LT1 cat-backs also use 2.5" mandrel bent pipe. I think that would be acceptable, but I remember a test posted on the forum that showed an LT4 that gained more peak hp from the company's 3" system over their 2.5" system. I say peak hp because that was the only data given.

 

my ide was to use the stock y-pipe, cut it behind the pre cats and weld it on to the collectors. Then use a replacement tube for the cat. All this is going throuh stock LT1 mufflers ( witch I have on now ). How much will that choke my preformance?

 

fish, do you need cats in Sweden? If you just want to run cats, the recommendation above is a good one. In any event I would dump the pre-cats. That whole Y pipe set up is very restrictive. GM even made an "export" Y pipe that did not have the pre cats. They are only there to help clean up the exhaust on start up because the main cat takes longer to heat up. Also, the Y pipe is also much smaller in ID, as it's a dual walled pipe for noise suppression. Incorporate a crossover wherever you can fit it. The Corsa LT1 systems have a 2 1/2" crossover pipe I believe just in front of the dual resonators. BTW, I just dumped mine, that's why I can tell you with confidence it's very restrictive! (1990 ZF)


[Modified by h rocks, 12:57 PM 4/10/2003]

 

I don't know how much it would choke your performance. I haven't seen any information on moving from a catless Y to a dual exhaust setup. If I had to guess, I'd say 10hp above 5500rpm ???

I would suggest you not weld any pipes to the collectors. It will make it very difficult, if not impossible to remove the exhaust. The collectors will have a 3 bolt flange. It sounds like you will be doing the work yourself. If that's true, I would look for a reducer, a short pipe with the 3 bolt flange to mount to the headers. Then you can weld your pipe onto the reducer. They come in many sized, including 3" to 3"



EDIT: The Y-pipe may come with ends like in the picture. If so, you can cut that like you suggested.


[Modified by Raistlin, 1:06 PM 4/10/2003]

 

i love my headman headers..i got my coated and wrapped....i welded o2 sensor right after all the pipes come together... and i cut out the pre cats and replaced all the piping back

So i am running full lenghts to 3 inch to to a 4 inch pipe...4inch pipe to cat (stock cat) then 4 inch out to 3 inch y pipe out to LT-1 camaro stock tips painted black! it sound like a indy car it if very quite at idle but when i get on it sounds like an import kind of...kind of weird...but i love it!

 

The Hookers I have are coated and have the AIR tubes, the EGR and the 02 sensor hole. They end WAY past the factory Y-pipe so you need to either buy the Hooker Y-pipe or run custom dual exhaust pipes.

 

krivera, I was going to suggest something similar to your setup. Mainly, if you go with a Y-pipe, use a 4" exhaust where the system is one pipe. In essence you've created an elongated X-pipe configuration. I think a 3" Y to a 4" or 4.5" single back to a 3" Y would be a great performer. I think Dr Gas had something similar on his website, but used a flat exhaust pipe where the two banks merged.

I personally use hedmans with a dual 3" exhaust with H-pipe, no cats. I made 254rwhp with 2.5" duals, no cross over, no cats with the hedman headers. I haven't re-dynoed yet.

 

I believe it is the Hooker 2149 that are coated and have all fittings already on for AIR and O2 sensors. Then they also have a Y-pipe (like 16770? or something similar) to fit them because they collect past where the stock pipe does.

 

here is the hooker Y-pipe


It's $139.95 from summit. The reducers are under $20 from summit. If you are going to cut and weld pipe, the reducers would save you a lot of money.

 

I wouldn't be surprised if you lost a few horsepower. Exhaust velocity is critical to making HP.

 

I was wondering if anyone has ever tested just the mufflers. I have read on this forum that LT1 catbacks are fairly decent, and a change in mufflers would be for sound and not performance, unless we are talking about huge hp cars, where an upgrade would be necessary.
I am using the LT1 mufflers (as the original poster does also) with my modified L98 mainly for the look, but I also didn't want a really loud car. So they suit me fine for those 2 reasons. How much power if any I am sacrificing over a set of
loud aftermarket mufflers?



[Modified by HeeHaw89, 9:08 PM 4/10/2003]

 

What is the benefit of having the EGR tubes on the 2149's vs. none on the 2151's? If I use the 2151's will it set codes or increase emmisions? Do either have holes for the O2 sensors and if not can these be put in after they are coated?

 

If your planning on running a cam with any amount of overlap as small even as the LT4 stock cam, the EGR is useless, the air systems becomes useless as more overlap is present in larger camshafts and or if you do not have cats. just some info for the group for performance. now if your emmissions tested for visual these will need to be in there, if tested with sniffer good luck, it will take some serious finite tuning to get a cam with any overlap below a 114 to pass, and i would not run the car for performance until it was retuned for the re-enrichment of fuel or you will be buying new pistons from a lean condition.

the 3" system is a performance plus for higher revving motors which need less back pressure at higher RPM. a low RPM motor will require less tube diameter simply because the volume of air it is moving will be less at its peak power RPM. therefore, a 5000rpm motor will likely perform very close with 2.5 system mandrel bent to a similar laid out 3.0" system with perhaps a slight decrease in torque from loss of low rpm back pressure. in the case of exhaust, there is a coefficient of tuning for a broad power band that suits the motor combination.

chris

 

What about 2151's, high flow cats, hotcam, heads, will this pass the sniffer in NC with a good tune?

 

Hotcam can be tuned to pass smog, but its not necessarily a tune 'up', its usually a detuning. Depends on whether you would like your PCM programmed after every sniffer test.

Youll still make more power than stock though.

 

so going from the hookers to my stock y-pipe would hold hp back on high RPM? Must I go 3" all the way to the mufflers?
ANd yes We need cat in sweden :(

 

No.

My rear Y-pipe is normal 3" into 2.25" mufflers. Car pulls to 6300 so it seems to be a non-issue.

 

No I'm confused. I'm planning on running LT's without cats. In the near future I was considering a LT4 Hotcam upgrade. Am I wasting money on the emissions stuff on the headers? What if I decide to go without. What all is required to do this?

Thanks

Eric