Interested in modifying the stock header a bit (pre-cat or pre-cat material removed) - new neighbor with excellent welding/fabricating skills. What material is the stock header constructed from?

Some older threads discussed this "poor man's" option a while back - any updated or new information out there on this modification?

Thanks for any responses.

 

I just gutted the pre cat and noticed a bit more tone. Not sure on any gains but as much crap as they had packed into that pre cat there has to be some gain.

 

its nothing special
just cut it open, remove what needs to be removed and weld it back together

MAG works fine ( wire: G3Si1, gas: 18% Argon / 82% CO2 )
Wig works good too ( an looks better to )

 

Contact "partsman" here on NAM. He had a thread on it before and did it to his car years ago.

 

I recommend going further than gutting the pre-cat, this way you can clean up the primary tube ends where they are squeezed together, and remove factory weld slag. Replacing the pre-cat makes a nice smooth collector.



A jig would need to be made for the original shape to align the pieces afterwards. The above example was made at Corky Bell’s shop. Since you are close to Atlanta I would send it off to Juston Poole 404-625-1882 to have him perform the work. He takes a different approach to the tubing, but the workmanship will be top-notch.

 

I'd opted to just store it in the corner of the garage and install an OBX header for 199.00

 

Thanks for the responses guys - can anyone tell me what material the stock header is constructed from?

 

I did remove the pre-cat a while ago, but I think the thread was started by someone else...

...my manifold looks pretty much exactly like this one Keith posted...

...it's some form of stainless steel, not sure which one.

 

Partsman:

Can you give me any thoughts/opinion on the pre-cat removal mod?

Any noticeable hp/tq gains?

Any difference in sound/drone/etc.?

Any problems?

Do you recommend this mod?

 

My first thought when I saw what was inside the pre-cat was that I don't know how the car even runs with that thing in the exhaust system.

I'm sure you have noticed how black the insides of your tail pipes and tips are...mine used to be like that too, until I removed the pre-cat. If I swipe my finger in the tail pipe now, there is hardly any black on it.

I didn't do a before and after dyno, but the car definitely felt smoother and quicker after.
I didn't notice any difference in the sound and there was no drone at all.
I haven't had any issues or problems at all...probably going on 2-3 years now.
I would recommend the mod on a mildly modified car...but if you upgrade to a better flowing head, the stock manifold design may not be the best choice.

Hope that helps.

 

I have a ported head with larger valves, the OE header flange ports are enlarged to match the head's modified exhaust ports, the car has lot's of oomph! It hasn't been a hindrance for me.

 

I knew that my last statement would draw a reply from you, Keith.
I wasn't exactly sure what kind of hardware you had in your car, so I tried to word it with some gray area.

 

Thanks Partsman; Keith for your responses. I believe I am ready to take the plunge.

One last question - any thoughts on using header wrap on the stock header?

Len

 

Any thoughts on header wrap on stock header? Anyone? Bueller?

 

There are plenty of people who have wrapped the stock manifold as well as an aftermarket header with no issues. There are threads about it on here.

 

The weld joining my pre-cat to the stock assembly snapped, so I ended up gutting out the pre-cat, rewelding the pipe back together and installed back in. Better sound and a wee bit more peppy feeling (Maybe just in my head)