Unfortunately data about S28 in Catalonia is sparse. The region wasn't tested by either Myres or Cruciani et al., and all the other regions tested in Spain had between 1 and 4% of S28 (except 6% in Valencia). Iberianroots
has the most extensive commercial data for Spain, but only reports 1% of S28/U152 for Catalonia, out of a very reasonable 193 samples. Most of the Catalan R1b is M269 or S116 (50% of the population) and SRY2627 (22%). It could be that some of the M269 members didn't test for subclades, but even so, there is at present 20x more SRY2627 than S28, so I don't see how S28 could exceed 5-6%, or 10% at the very most.