e63
it will run you 95K w/ options that you'll want. also consider this is largely a bodystyle change (which does look great IHMO). The DFI adds a modest bump in HP and the new DCT will probabaly be the biggest performance gain.
on the other hand, it's still largely the same engine as u got with the C63.
i was going to go with the e63, until i realized that in 2011/12 they will likely be coming out with a forced induction version. the mod potential on something like that is leaps and bounds better than with NA.
with that said, i love the feel of my NA engine in the C63. But modded turbos can be almost as linear.
so, i'm planning to wait. the benefits of waiting for the next gen engine may not apply to you, however.







