XV uses an Afco shock that is custom valved specifically to their spring frequencies, which are all matched to the particular body style and engine combination, using factory shipping weights and weight distribution. You bolt this kit on and forget it. I would liken their kit to a custom suit that is tailer to fit you perfectly.
Hotchkis and their Bilsteins and are revalved to work in a range of frequencies that are typically found in higher performing systems. Hotchkis did help develop this shock's valving before they offered torsion bars, so they are not precisely dialed in, but are closer than most of us could ever get them to be. Hotchkis has done a considerable amount of homework around improved geometry and adjustability. Perhaps there kit is better suited to the tinkerer who wants to dial in the suspension to best suit their needs. BTW, Hotchkis t-bars are 1.03, XV are 1.12. Using the suit analogy above, this one one from Mens Warehouse that is close to fitting but gets pants and sleeves hemmed to fit.
PST is a collection of aftermarket parts built by other companies that collected, packaged, and offered as a kit. Nothing inherently wrong with that or PST, but you can probably source all the individual pieces almost anywhere else. Are you sure that their kit price is for Bilsteins and not KYB, because they do offer both shocks. Personally, I buy all my suspension rebuild kits from PST, but have never picked up other hard parts from them. I believe PST is also offering 1.03 bars in their kits and Hemi style leaf springs out back.
