The original post states, "I know what's on the market but what is cheaper", so I think he is looking for a low cost solution and that would be the Topline Sport+ tapered spring and drilled drums thus in effect allow the fitment of the "modern alloys".

The main difference between the MaXX strut and the Kerscher is that the MaXX is adjustable in 1/2" slots and the Kerscher is fully adjustable. The strut is basically the same but as said the adjustability is the difference. The Kerschers are more adjustable but this would only be needed by a 'serious' racer that has to corner balance his car for the track. The MaXX are $300 less than Kerscher's strut plus the cost of overseas shipment, so it's all about cost effectiveness. The Kerscher has the advantage of the progessive spring and full adjustability that I would recommend for the track but on the street the MaXX do just fine.