Header/Exhaust System Design

[DEFIANT 7M]

Ok, I left this a bit undone and I know it's an old one. Sorry guys, I hope this info redeems me a little. Raptor Racing has a beautiful 6 into 1 header, unfortunately it will not fit the MKIII. I bought an OBX(knock off) 2JZ header:3d_frown:. The primaries are 1 1/2" big let down, its pretty but of no use to me. The plan was to modify it to fit the 7M, but once I measured the primaries I put it in a corner. Not one to give up, I noticed something earlier today. OBX has two headers a 5MGE and 7MGE,if you look at them they are very different. The price difference may explain why most have this on style vs the other MKII guys included.

Everybody seems to have this one http://www.obxracingsports.com/products.php?pk=966 The primaries are 1 1/2", and shorter primaries. But the cost of $150-180 looks more appealing. So everybody ends up with a Pacesetter(1 1/2" primaries also) or this OBX and see marginal gains.

But this is a much better header http://www.obxracingsports.com/products.php?pk=1820 Check out the primary pipe size:aigo:that's the o.d. dimension. I bugged a few people today the inner diameter is 1 5/8" perfect! Don't get sticker shock I've seen this header on ebay for $299-350. It's also a long tube design some what, O2 location is a need to fix area. But thats all I see. It seems to be the best header I've found that's not custom and available. It also seems to be close in design to the Trust header. I'm going to buy this one, if there is something not right I'll send it back this time.

Also I wasted about an hour chasing part numbers! OBX's website list one number ebay has another. Just look at the pics:icon_idea


My 2JZ header debacle:3d_frown:

 

[MPR]

Just read through this entire thread. Reading more and more of how restrictive the stock manifold and exhaust system is the the ge, is pushing me more and more towards replacing the whole system. Plus I have a leak at the flange where the stock collector bolts to the cat as well as a small crack developing in the manifold, so it's all a good excuse to replace everything...lol.

If you relocate the O2 to one of the 1-3 primary collectors, is the reading still accurate enough? Only reason I ask is because the stock setup the o2 is exposed to the exhaust from all 6 cylinders...

One more question, is the exhaust manifold flange/bolt/port pattern on the 5m and 7m exactly the same? Meaning can one buy a 5m header and modify as needed to fit the 7m?

 

[DEFIANT 7M]

I just typed a nice reply and my crapberry lost it. On the O2 mount everybody mounts it @ the merge to 1 pipe. We do share the exact same flange as the 5M. Just a little clearencing of the flange to clear the distributor is needed on both engines. I like 3" exhaust you may be able to find a nice turbo cat back system. Or just make your own. Excuse any alternative spelling my phone and I are going to have a big hammer meets phone session very soon!

 

[MPR]

Mine is a bone stock NA 7mge so I don't need or want a 3" system. 2.5" is ideal.

Thanks for the info on headers. So then maybe it's best to find a good 5m header with the correct primary diameter and collector design and go with that, remembering that some modifications may be required to fit the 7m MK3. Unless one can get their hands on one of those TRUST or HKS units...

 

[DEFIANT 7M]

Hey no problem.. Yes it looks like the 5MS have the best designs provided the primary pipe is the right size. I think just about any header will need to be modified no matter what. Just the designs glitches