Are these headers bigger than 986S headers? Please help!!

[BoxsterLewis]

So I spoke with Todd and he said the 987 headers are about port size, i think the difference between the 3.2/3.4 is the primaries..Thanks for the information Blue-S!

[BoxsterLewis]

K so the difference in part numbers between Cayman S and Boxster S 987 "987/21" and "987/22" for Cayman and 987/01 and 987/02 for the Boxster. Anyone have ANY idea what the difference b/w the two are?

[Blue-S]

The parts catalog (PET) is back up on Porsche's website. I was able to determine the following:

* My headers (part numbers 987.113.103.08 & 987.113.104.08) are actually from a 2006 Boxster, NOT a 2006 Boxster S.

* The 2006 3.2L Boxster S header part numbers are different from the ones that I have.

* The 2007+ 3.4L Boxster S header part numbers are different from 2005-06 Boxster (2.7L) and 3.2L Boxster S.

* The 2007+ Cayman S (3.4L) header part numbers are almost the same as the 3.4L Boxster S headers; only the last two digits are different.

* The exhaust manifold gaskets (between the cylinder head and the header/manifold) have superseded so that the same part number now is used on many Boxster, Cayman and 996/997 911 vehicles. Gasket part number 996.111.107.55 was originally listed for a 3.6L 911 with the X51 performance package, but it is now listed for Boxster & Cayman too. This means that the port openings in that gasket are the same size as the exhaust port openings in the 3.6L cylinder head.

With this information in mind, I drove to the Porsche dealer and compared one of my 987 Boxster headers with the exhaust manifold gasket (part number 996.111.107.55). The openings in the gaskets were an exact match for the port openings in the headers! This means that my stock 2006 Boxster headers will fit the exhaust ports of a 3.6L engine very well.

This raises the question: If the 2006 Boxster 2.7L, 2006 Boxster S 3.2L and 2007+ Boxster S/Cayman S 3.4L headers are different from each other, what's the difference? I would have to see and measure a Cayman S/Boxster S header to get a better idea about that. Given that the port openings in the Boxster 2.7L header are as big as the 3.6L ports, it's entirely possible that the difference between the headers might be something that cannot be easily seen or measured: the precious metal content in the built-in catalyst. This is not as far-fetched as it sounds, since platinum & rhodium are REALLY expensive. What if the difference is in the catalyst substrate type and/or the cell count? The 2006 Boxster 2.7L headers appear to have ceramic substrates. Regardless, I would love to know the tube diameter on the various 987 stock header primary tubes and the header outlet pipe.

2006 Boxster 2.7L stock header primary tube in straight section = 1.65" OD




2006 Boxster 2.7L stock header outlet tube = 2.15" OD



I would welcome similar measurements on known Cayman/Boxster S 3.4L stock headers. That would provide the final piece of the puzzle...

[Paul]

The Cayman S stock system on my 3.6 has 1.64" header pipes and the collector pipe is 2.21" The B&B system that I took off has 2.25" collector pipes.

[berty987]

An old thread I know. The 987 3.2 headers are a 3 into one equal branch design rather than a tree arrangement on the 2.7 and 3.4 987 as pictured. Having dyno'd both designs on my 3.2 , I can confirm the 3.2 headers flow much better and give more power, they are also without the pop and crackle of the 3.4.

I'm interested in whether the 3.2 headers can be further improved by removing the ridges of weld on the flange at the inlet. There are some pictures i posed on the planet9 website under the articles section on decatting manifolds that show the two designs better.

What I can confirm is decatting either header doesnt work , it does give a better top end power figure but at the expense of the mid range peak torque figure.