986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post

admlmm · 10-20-2007, 10:35 PM

Sorry if this does not exactly fit this thread but here is my recent experience with headers. I have a stock 2002 S (in Australia) and I replaced the OEM headers. These do not have the inbuilt 1st set of CAT's like the US ones seem to have judging by the other threads on the subject. The OEM headers have 34mm external diameter pipes with 40mm (approx) internal diameter (ID) collectors. I installed a set of aftermarket T304 headers (Porsche Tuning) that look like those attached . They have 45mm ID pipes with 50mm ID collectors. I chose these because they had 45mm ID pipes whereas it looked like the Maxspeed ones, whilst looking the same, had only 38mm pipes. Their collectors were the same 50mm as the others. The Porsche guy commented to me that the after market headers looked very well made but showed me that the Gambella ones were better due to smoother internals from the welds. He commented he too would not have spent the extra money on the Gembella's as mine seemed pretty good. You can see in the OEM shot how poorly the OEM pipes merge into the collectors compared to the aftermarket ones. I videoed both before and after and ran the recording through a sound measurement program my son found on the net. Sorry the forum tool will not accept the videos. We measured the camera distance to the exhaust pipes to keep the same. We tried to keep the revs the same but this is difficult to achieve for a couple of hacks messing around in the garage. The results are by no means scientific but indicated to me that the car is actually slightly quieter now than with the original headers. This is supported by my "impression" of driving it. In fact it is now so quiet I cannot believe it is the same car. The car appears to spin out through the revs a lot quicker and seems to have more punch. I have a fairly serious corkscrew ramp at the office and used to just let it idle down with the engine braking keeping my speed in check. I now have to dab the brakes as it seems like a lot of back pressure from the engine has been relieved. I did want a more sporty sound and if I got more power that would be a bonus. I am pretty sure I achieved the latter but not the former. I guess I will have to fit a cat back exhaust now to get that sound. I was frightened off installing the headers myself by all the talk of broken studs and got the local Porsche shop to do it. As luck would have it no broken studs and probably about an hour for the total job. The car only has 44 thousand kms (27 thousand mls) and has never seen serious rain or cold weather so maybe that is why the studs were not frozen. No CEL's which is as I expected as I have not messed with the O2 sensors. Now, why would larger diameter pipes and collectors and better designed merges translate to lower engine back pressure and less noise? My guess is more laminar flow of the exhaust gasses than the turbulent flow created by the terrible OEM headers. That translates to less pressure loss from the headers and an increase in efficiency. Some other observations I have that may help others. The Fabspeed system looks very well made but I will agree is relatively expensive to other after market systems. From their video it seems they claim an advantage over the others by having 2" inlets into their muffler compared to 1 and 3/4 of the others. As much as I am attracted to that I can now not easily fit their system as the bulge in the intermediate pipe is a resonator and not a CAT so I would then have no CAT which would not be good. Their system has the CAT incorporated in their header so you really have to fit their entire system to make it work easily. It seems as though they have also altered the rear connection position between the intermediate pipe and the muffler so I cannot easily just fit just their muffler. I will probably end up buying Che's muffler as it will bolt straight onto my OEM intermediate pipe (containing my CAT). The only choke I will then have is the smaller diameter OEM intermediate pipe and CAT which may be another project for the future. In hindsight I probably should have just gone for the full Fabspeed system in the first place.....

10-20-2007, 10:35 PM	#17
admlmm Registered User Join Date: Jan 2007 Location: Australia Posts: 4	admlmm Sorry if this does not exactly fit this thread but here is my recent experience with headers. I have a stock 2002 S (in Australia) and I replaced the OEM headers. These do not have the inbuilt 1st set of CAT's like the US ones seem to have judging by the other threads on the subject. The OEM headers have 34mm external diameter pipes with 40mm (approx) internal diameter (ID) collectors. I installed a set of aftermarket T304 headers (Porsche Tuning) that look like those attached . They have 45mm ID pipes with 50mm ID collectors. I chose these because they had 45mm ID pipes whereas it looked like the Maxspeed ones, whilst looking the same, had only 38mm pipes. Their collectors were the same 50mm as the others. The Porsche guy commented to me that the after market headers looked very well made but showed me that the Gambella ones were better due to smoother internals from the welds. He commented he too would not have spent the extra money on the Gembella's as mine seemed pretty good. You can see in the OEM shot how poorly the OEM pipes merge into the collectors compared to the aftermarket ones. I videoed both before and after and ran the recording through a sound measurement program my son found on the net. Sorry the forum tool will not accept the videos. We measured the camera distance to the exhaust pipes to keep the same. We tried to keep the revs the same but this is difficult to achieve for a couple of hacks messing around in the garage. The results are by no means scientific but indicated to me that the car is actually slightly quieter now than with the original headers. This is supported by my "impression" of driving it. In fact it is now so quiet I cannot believe it is the same car. The car appears to spin out through the revs a lot quicker and seems to have more punch. I have a fairly serious corkscrew ramp at the office and used to just let it idle down with the engine braking keeping my speed in check. I now have to dab the brakes as it seems like a lot of back pressure from the engine has been relieved. I did want a more sporty sound and if I got more power that would be a bonus. I am pretty sure I achieved the latter but not the former. I guess I will have to fit a cat back exhaust now to get that sound. I was frightened off installing the headers myself by all the talk of broken studs and got the local Porsche shop to do it. As luck would have it no broken studs and probably about an hour for the total job. The car only has 44 thousand kms (27 thousand mls) and has never seen serious rain or cold weather so maybe that is why the studs were not frozen. No CEL's which is as I expected as I have not messed with the O2 sensors. Now, why would larger diameter pipes and collectors and better designed merges translate to lower engine back pressure and less noise? My guess is more laminar flow of the exhaust gasses than the turbulent flow created by the terrible OEM headers. That translates to less pressure loss from the headers and an increase in efficiency. Some other observations I have that may help others. The Fabspeed system looks very well made but I will agree is relatively expensive to other after market systems. From their video it seems they claim an advantage over the others by having 2" inlets into their muffler compared to 1 and 3/4 of the others. As much as I am attracted to that I can now not easily fit their system as the bulge in the intermediate pipe is a resonator and not a CAT so I would then have no CAT which would not be good. Their system has the CAT incorporated in their header so you really have to fit their entire system to make it work easily. It seems as though they have also altered the rear connection position between the intermediate pipe and the muffler so I cannot easily just fit just their muffler. I will probably end up buying Che's muffler as it will bolt straight onto my OEM intermediate pipe (containing my CAT). The only choke I will then have is the smaller diameter OEM intermediate pipe and CAT which may be another project for the future. In hindsight I probably should have just gone for the full Fabspeed system in the first place.....