Interesting entry, especially considering I have a 4.9 in my '91 DeVille. I've been very impressed with it's smooth, silent operation while still managing to haul ass—and at 200K miles no less. Responsiveness is much better with the new Bosch fuel injectors from
FiveOMotorsport.
Besides the larger displacement and port fuel injection, how else is the 4.9 improved from the original HT4100? Does it still have iron heads? Any ideas why Cadillac put iron heads on an aluminum block? That makes no sense.