Update on new PST 1.03 Torsion bars.

OK, I was figuring PST would likley use the same source and steel and you would get reasoanble consistency in back-computing.

Interesting chart in the context of this discussion. Just as an FYI for the A body T-bars, starting with the 1.09" at 300 lbs/in rate as the reference and back-computing other rates from that, here are the Diameter/Advertised rate/Computed rates:
1.14/350/358
1.09/300/300
1.04/250/248
0.99/200/204
0.92/150/152
0.89/130/133

So they are back-computing within 2% or so of the advertised rates and I suspect the advertised rates were rounded to the nearest 50 or 10 lbs. And most cars can't be tuned that fine anyway with other things like bushing stiffness involved. Now you got me wondering why PST is not giving the data, 'specailly since you are looking for such a fine difference. And who measures their T-bar diameters with the paint on and who measures them with the paint off! lol

BTW, edit to add: the same type of back-computed comparisan for FirmFeel bars with 300 lb/in as the reference, is:
1.18/370/370
1.12/300/300
1.06/252/240
1.00/195/191
0.94/155/149
0.88/115/114

Just keep in mind that the published data is measured data (we presume!) and is subject to the errors of their measurements. The 'wire diameter to the fourth power' relationship is a laws of physics thing that simply IS, and when springs deviate from that it is due to manufacturing variances, spring end effects, and measurement accuracy, etc. Getting springs of the SAME rate that are within a few % of each other is doing pretty good.