I agree with Mark's comments as I checked with APR regarding the oil restrictor issue as many on Vortex were fitting them. I haven't put one on my car as advised by APR but since the re build I find there is no oil smoke issue 'except' if the car sit's on idle for over 15-20 mins it can puff initially but is soon burnt off when driven.
Everyday usage is fine but it was worse prior to the rebuild due to worn valve stem oil seals.
Mark, do you offer a 'lifetime' warranty on your manifolds? It was something that really pusuaded me when Guy in Australia offered this on his APR manifold design for RHD configuration....gives peace of mind re cracking issues.