mag header question

kishon55 · Post by **kishon55** » Mon Dec 03, 2012 9:38 pm

Does a mag header make any diffrence in a se with bolt ons

titansxt · Post by **titansxt** » Mon Dec 03, 2012 9:54 pm

You might flow out better but I don't think you will see a noticeable difference. I'd say it is not worth the trouble.

Post by **occasional demons** » Mon Dec 03, 2012 11:38 pm

The Magnum header does not have an o2 bung, so you will need one welded in. Other than that, it is an excellent replacement for a cracked manifold. You can get them relatively cheap, they hold up well, and fit perfectly with your oem exhaust. You even have the option of factory heat shields.

kishon55 · Post by **kishon55** » Tue Dec 04, 2012 12:18 am

Mine isnt cracked just wanted a better header I have a 2.5 in exhaust mag intake manifold cai ive been hearing it wont a diffrence is this true

INVUJerry · Post by **INVUJerry** » Tue Dec 04, 2012 9:15 pm

The more you do to the car the more it will help. I say go for it.

ZeroChad · Post by **ZeroChad** » Wed Dec 05, 2012 2:40 am

You're going to have a weird step down from the standard head to the magnum header ports since it's a bigger ID port.l...I really don't know if that would hurt or help flow. No one spends money on dynoing one part at a time lol.

NickKo · Post by **NickKo** » Wed Dec 05, 2012 7:01 pm

ZeroChad wrote:You're going to have a weird step down from the standard head to the magnum header ports since it's a bigger ID port.l...I really don't know if that would hurt or help flow. No one spends money on dynoing one part at a time lol.

I have wondered about that, too.
The Magnum header, is almost too big, compared to the Standard SOHC cyl. head Exhaust ports.

For a 'standard' SOHC cyl. head, I think an E-bay or Pacesetter header, might be better, for a 'mild' build.
But again, I haven't dynoed the two, either.

- Nick

trojmn · Post by **trojmn** » Wed Dec 05, 2012 9:22 pm

the 1.625" mag header are IMO too big even for the mag head, though it would be less of step there than on a standard sohc.

if your going to do it, do it, but in almost any case (mag or not) if you cant fit a LTH a 1.5" header would be better as long as the collector isn't completely garbage.

Post by **occasional demons** » Wed Dec 05, 2012 11:08 pm

I didn't notice any gain or loss using the Mag header on my SE head.

The way I see it, the runners are so short, and the added diameter probably is just enough to give the gasses a little expansion room, like a step header.

If the larger diameter was on an LTH, then it might not be so good.

The stock Cat flex joint kind of kills most of what you gain anyways. It only has about a 1.5" I.D. Could be one of the reasons an LTH makes more power too. You are eliminating that bottle neck in most cases when adapting the down pipe for an LTH.

trojmn · Post by **trojmn** » Wed Dec 05, 2012 11:18 pm

occasional demons wrote:The stock Cat flex joint kind of kills most of what you gain anyways. It only has about a 1.5" I.D. Could be one of the reasons an LTH makes more power too. You are eliminating that bottle neck in most cases when adapting the down pipe for an LTH.

I never noticed the restriction in the flex pipe. I'll keep an eye on it.

I'm planing a 1.5" ST legal header/merge/cat should be interesting or at the very least no worse.

what I did notice was the parts store "R/T" collector gasket was WAY too small. from my autox thread:

PSA... local parts store magnum exhaust gasket is bit smaller than ideal. I'm not sure how much that was actually hurting things but it sure wasn't helping any. The short story is i did a magnum head swap & timing belt PM etc last month when i was suffering a massive sinus infection/flu/plague whatever. I was wrapping it up LATE Sunday night and noticed the mismatch... then promptly forgot about it.

I wondered about it all damn week, then got time to drop the exhaust the next weeked. that soot ring is about 3/16-1/4". 5 min with a good tin snip took care of it.

While you're there clean up the weld boogers! ports looked about the same. not that they were ANYWHERE close to being in the exhaust stream

Post by **occasional demons** » Thu Dec 06, 2012 12:34 am

The one on the left is a Magnaflow direct fit. The mis-match of that gasket would mean nothing on a MagnaFlow.

But you can sort of see how small the ID is compared to the header/Manifold outlet. I measured the oem a month or so back, when I was looking for some other stuff. Very close to 1.5" with a tape measure.

trojmn · Post by **trojmn** » Thu Dec 06, 2012 12:41 am

The magnaflow is a bit wider in the flexpipe area than OEM?

Post by **occasional demons** » Thu Dec 06, 2012 1:16 pm

Not really. The inlet hole differences sort of creats an optical illusion. Where the oem flange sort of has a bit of transition, the MF is an abrupt wall with a hole in it.