Because there's absolutely NO reason to. There isn't even an upgraded set of turbos that one can buy that could even begin to utilize the extra flow the cams would provide. The stock turbos can be easily max'ed on the stock cams.
'13 Black Sapphire Metallic 335is DCT, MHD stage 1+FMIC/E20, Wagner Evo 2
'14 991 GT3, Sapphire Blue / Black, 11.30 @ 124
'07 997 TT 6MT, Arctic Silver/Sea Blue: FBO E85, stock turbos: 5.9 60-130 (now with 656 whp, 700 wtq)
Prev: 2 FBO 335 6MT, and '15 F80 M3 6MT