Aluminum Head /6

Exactly, you're in Los Angeles which is basically sea level... have you tried driving up a 6% grade at 7000' above sea level in said slant-6 car? Or even try to pass someone at 75 mph on flat ground at 5000' above sea level?

Ask anyone who's moved to Colorado from another state they'll agree it felt like their car lost 2 cylinders.

@Killer6 go ahead and school me I'm all ears. Never bothered to mess with a slant because on paper they seem more like a stationary industrial or heavy-duty truck engine. I know they have 4-main-bearing cranks which are lighter than the Jeep 4.0s. I also know the 4.0 doesn't have the most rigid block, and the machining tolerances were pretty terrible from the badly worn-out manufacturing tooling. It just seems like you have to modify pretty much everything on a slant for it to make decent power, and by decent I mean over 200; not just "hey my slant feels pretty peppy compared to some other worn-out V8 car I had". Put a proper header on a 4.0 with the 1999-up ram-tuned intake manifold and a mild cam and it'll make 250+ HP no sweat. So seriously tell me where I'm wrong, might make me not dislike slant-6s so much which would be a good thing.

EDIT: sorry I'm hijacking the thread feel free to PM instead...
Exactly, I don't want to hijack this thread, not sure what part of My post is ambiguous. Many modern engines have small bores in relation to the stroke, but the heads are up to the task. The slanty head needs larger valves & good port work to run like one would expect a modern 3.7-8 liter 6cyl to run. Even the 3.8 in a late '90's Grand Caravan or T&C runs well with only 2 valves inline and w/o variable cam timing, active intakes, etc.and those things curb at 4000#+.
A poor factory head is an argument FOR an aftermarket head, not against, so.....
The subject of this thread does not represent what would be desired particularly, but it is a piece of history, that is all.