Also remember, currently neither header works for the '06-'07 6s due to a slight layout change done underneith (the rear will probably work but the front won't, will hit the oil pan). The CP-E one's I am trying to gather enough interested people so CP-E will make some for the '06-'07 (see link in sig). The MSDS you might be able to get to work but will have to pay someone to do some custom pipe fabrication from connectors to the y-pipe. And granted, an actual apples to apples comparison has not been done. Instead in a previous topic I posted a spreadsheet of current dynos (
Located Here) for each to give an idea of where the power gain is at and the percentage gain. But due to dyno differences there is some missing info and flaws, so take the gains over each other with a grain of salt and instead focus on power improvement and where the power develops.
Shorties are good for quick bolt-on and mild to little other mods to take advantage of them. Shorties also tend to build up power from low to mid range and not so much up top. Long tube equal length headers are typically more powerful in the mid to high but do have gains in the low (typically within a few percent of the shorties) but tend to have larger gains the more you modify the car. Due to the latter, people who plan to do the full shebang at some point or close to it (headers, exhaust, intake, manifold, throttle body, cams etc.) may benefit more from the long tube.
Other considerations are ease of installation. Shorties are easier to install versus longtube (which you have to finesse a bit). The MSDS you have to cut into the alternator shielding to work. The longtube relocates the alternator and supplies you a longer belt for the change. Correct me if I am wrong, but the MSDS headers were designed for the Duratec engine in general and not specifically tuned for our car with exception to the y-pipe connector. The CP-E headers were designed from the ground up for our car and were tuned for our car. Not trying to make one a negative over the other, just pointing out where they came from (and I may be wrong on this). Either way you will get gains, it just depends on how and where you want the gains and what are your future plans when it comes to mods.
As for the CP-E headers not being trouble free, that was with the earlier versions and I believe that problem has been solved and remedied in all newer headers (part of the reason you don't see them in stock, the final touches are being put on the design before being sent back out to Kooks for manufacture, they may have already been sent out). The issue was due to the cats rattling apart, which was fixed by another set of cats that were placed to close together and rattled, and are now done with spun cats and the distance between them should not cause them to touch. I hope this helps and welcome to the community.
:seeya:
Paul