Euro headers are a direct swap with the highly restrictive US header/cat version. The next piece, catalytic converters/silencers, are also different between the US and Euro versions although look identical. Swapping all should yield 11 HP and 17 lbs/ft torque (crank) and smooth out the power curves. Anyone venture to guess what the header alone would yield? And can it be fitted to the US catalytic section? I'm trying to decide on a first mod...lightweight flywheel/clutch vs. Euro headers. Cost is close to the same. $1200 vs. $1700 plus installation. From there, next mod is a 3.91 final drive. Options are Dinan or ACS.