So you have euro manifolds with true dual exhaust? Yeah, all US Spec cars had crappy bottle neck exhausts, not just yours and the 500s. ALL of them! Yeah, mine may have a little "bigger" cam, but not enough to make a real difference. In the 420s, the 86s and 87s were almost the same in power output between euro and US. Then in 88, they bumped the compression a point to 10:1 (to compete with BMW) and that gave it about a 20 HP boost for KAT models. All US cars always had and always remained at 9:1 compression all the way to their demise in 91...which always kept the US HP levels to pre-88 euro numbers. Another reason mine may not feel as torquey down low is because I may have a high high rear end for high speed driving, whereas the USs may have had a lower geared rear end to meet the needs of most US roads. I'm not sure if the diffs are different, but there's a good chance.
'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.
"A Mercedes-Benz is like a fine wine, it only gets better with age."