Sky,
Bekkers dose sell an awsome set of headers for the M103 engine but be prepared to pay $1500 for them. I port matched and coated my original headers for a tenth of the cost. I'm sure there is not much difference in performance between the two. you could probably have a nice set of headers custom made for a reasonable price but still don't plan on any performance boost without a bunch of other modifications. i enjoy modifying my M103 engine trying to squeeze all the hp i can out of it on a budget.
Good Luck!
Adam

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Current Stable:
01 ML55 AMG
92 500E (a few mods)
87 300E (lots of mods)
00 Chevy 3500HD Diesel Box Truck
68 18' Donzi Marine
06 GT i-Drive7 1.0 Mountain Bike (with GPS!)

PREVIOUSLY OWNED:83 300SD, 87 420SEL, 88 420SEL, 90 420SEL, 86 560SEL, 86 190E 2.3-16V AMG, 94 E320