I didn't check the specs for width on the Cobras for comparison to the Dunlops, but the front Cobra definitely does look chunkier and better (better rounded too) than the Dunlop. It seems the rear 140/90 Cobra is 143mm wide - 1.5mm more than Dunlop, which would suggest, if the front 130/90 Cobra is 6.5mm wider than the same size Dunlop, that Avon has gone for a wider front in proportion to the rear, for the same front-rear size combinations. Might have something with the shape of the tyre patch and how much of it is actually useful at lean.EDIT:
Acc to Cobra's specs, they are 167mm wide whereas stock Dunlop is 141,5mm. It's not 20mm. It's whole 25 (and a half!). It does make a difference!
BTW, Front 130/90 Cobra is also 6 (and a half) mm wider than stock