The weight savings is less than people think. There was a thread where HemiDenny provided a bunch of weights for his coilover conversion and I weighed a bunch of stock parts. After everything was said and done we determined that a HDK coilover conversion was-
50 lbs lighter than the OE K member and suspension with factory power steering (vs HDK w/ power rack)
35 lbs lighter than an OE K member and suspension using a Borgeson power steering box (vs a power rack)
31 lbs lighter than an OE K and suspension w/manual steering (vs a manual rack)
And yes, if you go OE K and OE power steering to a manual rack the savings is about 70 lbs. But that's because the OE power steering is such a turd, even going from OE power steering to OE manual steering saves 40lbs. If you compare the OE K and manual steering to an HDK and power rack it's only a 9 lb savings.
A more detailed break down is here Anybody running the RMS AlterKation? Was it really worth the cost?
That also doesn't include any weight savings on the OE parts. If you run tubular LCA's and such you can shave some weight off the OE side too. It's not much, but if you care that much about a few lbs it can be done. On that note, my OE numbers are with 1" torsion bars.
Ok, let's get real. Half of that is BS.
Header fitment- yup, that's true. Much easier without torsion bars.
Handling- 100% false. You can handle just as well with torsion bars. Hotchkis cars have handily beaten RMS equipped cars. There's nothing special about the MII suspension from a handling standpoint.
Alignment- What does that even mean? I bet I'm running more extreme alignment numbers on my torsion bar car than you are on your RMS car. -1.1° camber, +6.5° caster, 1/16" toe
Looks- If you're buying suspension for looks, you get what you deserve
Weight loss- 31 lbs manual to manual. Ain't that much.
oil pan fitment- I suppose? There are plenty of aftermarket pans that fit the stock K. Or mostly so. I'm ok with the small notch I knocked out of the engine mount for my Milodon road race pan. Lots easier than a $5k hit for pinto suspension.
Let's not forget the loss in turning radius when you do a coilover conversion. Or, the additional frame stiffening needed to account for the fact that the Mopar chassis was supposed to carry its suspension loads in its crossmember and K frame, not on the frame rails/shock mounts/firewall.
