NA racing cams for professionally built high rpm engines with high compression, ported cylinder head and well designed intake and exhaust system. Great with 7A based rotating assembly and stroker kits. More top end power than the 194-D cam, pulling to around 10k+ rpm depending on engine. Kelford recommends VVT delete on intake, using adjustable gears for fixed timing. Kelford Cams recommends KVS51-B valve spring.