I was not attempting to test torsion bar stiffness, I was just did the "fender bounce" out of curiosity after I installed the bars, and was using the same fender bounce on my Scamp as a reference, so I am not sure that I agree with your statement that it was meaningless. I performed an impromptu "experiment" on 2 similar vehicles, and observed 2 different reactions to the same input. I also took into account the blown out shocks as a factor in the differing results.
Maybe "meaningless" is a little harsh, but the bottom line is that you're conducting an "experiment" while you have a bunch of uncontrolled variables (shocks, ride height, bump stops, alignment, different car, wheel base?, etc). That's a great way to get a "result" that isn't accurate or the one you expected. The shocks will make a much bigger difference than you might think. You're comparing a great set of shocks that are pretty firm (bilsteins) to ones you know are blown.
Car was at stock ride height with the stock torsion bars and regardless I did not perform the bounce test on the car with the the 318 bars, I used my Scamp with 1.03" bars as the reference, and it has trimmed bump stops with plenty of wheel travel, because I might not be the sharpest tack, but I am sharp enough to trim bump stops, and not drive around with the suspension sitting on the bump stops.
By stock ride height I mean you actually set the ride height to factory specs, measured the whole A-B thing on the LCA's and set it according to the FSM. Not just that the car is the same height as when you got it. Most people drive these cars around somewhat lower than stock, because they never actually measured and didn't account for the car lowering as the torsion bars age.
Maybe you are "sharp" enough to know when your car is on the bump stops, but let me tell you, I have talked to people on this site that said their car "handled and rode great" while it was in fact sitting on the bump stops the entire time. It's not even about being smart, some people just don't know. With stock torsion bars, even at factory ride height, the bump stops come into play quite a bit more than most people think. Put a dab of grease on the tops of the bump stops and go for a drive, you may be surprised. The stock bump stops are progressive and pretty soft at first, especially the LCA bump stops. They were designed to act as part of the suspension, and it can actually be somewhat difficult to know when they start touching unless you're driving the crap out of the car. Around town with stock suspension parts you can be using them all the time and not even realize it, it's not very noticeable unless you're slamming down on them and fully bottoming out the suspension travel.
Why would I not believe you?
Lots of people don't. Like I said, I've gone back and forth with people about their car actually
sitting on the bump stops while it was at ride height that didn't believe me until I told them to take a picture and post it. It's an internet forum- you don't know me or my level of experience with these cars. Plenty of information on the 'net (and this site) that isn't fully accurate.
Regardless of all that, I would bet that the difference you're getting with your "bounce test" has very little to do with the torsion bars themselves. I suppose it's possible there was some kind of manufacturing error at Sway-Away, but everything I've seen from them has been very high quality. Which means something else is going on.
