row headers

[The Radium King]

the reason i noted the part number is, if you go to the USA PET, it is for a 2.7/3.2 L boxster w/ cats (the 2.5 L has a different part number). any USA exhaust made 97 to 99 would not have cats but be for a 2.5 L. so, the assumption is that porsche used the same part # for headers with and w/o cats, and just issued the appropriate part by region.

knowing for a fact the uk and aus 2.7/3.2 L boxsters do not have cats on the headers (these are preheat cats required to meet USA emmissions) one can assume porsche felt the best performance was achieved by locating the remaining cat on the mid pipes. so, if one were looking for the best performance mod, it would be to use catless headers and not catless midpipes (and complete catlessness appears to kill low rpm torque). there are those cheap ebay headers out there, but welds, steel quality and flanges have been questioned, and the size of the primaries is a bit large, resulting in decreased low rpm performance. as an option to $2000 headers, i was thinking of row headers instead.

[Johnny Danger]

Originally Posted by The Radium King

the reason i noted the part number is, if you go to the USA PET, it is for a 2.7/3.2 L boxster w/ cats (the 2.5 L has a different part number). any USA exhaust made 97 to 99 would not have cats but be for a 2.5 L. so, the assumption is that porsche used the same part # for headers with and w/o cats, and just issued the appropriate part by region.

knowing for a fact the uk and aus 2.7/3.2 L boxsters do not have cats on the headers (these are preheat cats required to meet USA emmissions) one can assume porsche felt the best performance was achieved by locating the remaining cat on the mid pipes. so, if one were looking for the best performance mod, it would be to use catless headers and not catless midpipes (and complete catlessness appears to kill low rpm torque). there are those cheap ebay headers out there, but welds, steel quality and flanges have been questioned, and the size of the primaries is a bit large, resulting in decreased low rpm performance. as an option to $2000 headers, i was thinking of row headers instead.

I agree with your assessment that Porsche, as well as a good many high end tuners, believe that the best performance is achieved by utilizing individual headers in conjunction with cats that are located further down stream . This allows for greater freedom with respect to designing the length of primaries, using different diameter piping, incorporating a real merge collector ect .... And this was an approached that I greatly considered as my final choice for an exhaust system. However, during the process, I discovered that it was extremely difficult to find high quality low cell cats that were designed in such a way that they were compatible with the overall system . And, for some reason the ones that I did discover were either the wrong cell count or unjust in their cost . And, at 400 cells (and I've heard from some sources that they're as high 600 cell), I completely dismissed any idea of retaining the oem secondary cats. They're arguably the most restrictive part of the oem system .