Based on my understanding, Progress measures its numbers differently than JB and CS.
Progress has measured its stiffness as X% as stiff as stock.
JB and CS has measured their stiffness as X% stiffer than stock.
So for Progress, 231% as stiff as stock actually means 131% stiffer than stock and 303% as stiff as stock actually means 203% stiffer than stock.
For James Barone, 155% stiffer than stock actually means 255% as stiff as stock and for Corksport, 130% stiffer than stock actually means 230% as stiff as stock.
Therefore for both JB and CS, respectively, JB is stock multiplied by 2.55 and 3.65, and CS is stock multiplied by 2.3 and 3.2.
Progress's numbers are good, and I can't speak to Racing beat because it's not listed on its website.
But for JB, my understanding is that the numbers should be:
867 lb./in. for less stiff
1241 lb./in. for more stiff
And CS should be:
794 lb./in. for less stiff
1104 lb./in. for more stiff
These numbers make sense to me based on Progress's listing of:
The numbers do not vary as wildly among the different brands now.
Yeah, this was what I initially thought, and it does make a lot more sense.
I've changed the first post to reflect these numbers, and changed the wording a bit to make sense of it.
However, I'm still not entirely sure if this is the proper way it's calculated.
Maybe one of the venders like JBR or Corksport forum guys could chime in on it.
I went ahead and purchased the Progress bar. Hopefully there isn't too much of a delay before shipping, since it's still not listed as in stock.
Please update us when you receive it!
Two reasons: 1) I like the Billet brackets of the CorkSport bar better...and they also have Zerk fittings so you can more easily re-grease. I've had cars with aftermarket sway bars installed before, and having to remove the brackets to re-grease is a pain. The Progess brackets have no fittings to re-grease - if there are they are not shown in the photo's. And 2) I thought that by looking at the numbers (% stiffer than stock), the Progress was stiffer at the softest setting than the CorkSport at it's stiffest? So I thought it might be too stiff for the street. Now looking at what parkinskin posted, looks like I understood the numbers wrong? Confusing.
The brackets are a good selling point.
And yes, the numbers are quite confusing, due to the wording.