BMW N46 Oil Usage through guides

BMW, 16v 4 cyl, N46 eng. The exhaust guides wear, the ex valve stem seals go hard, and oil almost pours down the guides. BMW say fit new head, nobody makes bronze guides for them. Not BMW, NWE, or Precision. So I made a set from cast iron blanks ( NASONĀ  PVG2935 ) ( these are used in RB20,25 & VG30). All you need to do is shorten them. I charged them $380 to supply blanks ($2 ea), make guides (shorten) and fit them, normal P/T, V/G, and V/G on top of that $840 in total ( Pricing date 15/1/2013)