From what Casey at XAT told me yes you will lose the VVT of the s14 motor when adding aftermarket cams. I can't really comment on the second part except for that I know the vvt motor is a better motor with just basic bolt-ons(HP wise) but from what I understand about the SR's(which is very little) the s13 is the way to go when making big power due to the head design and better flow characteristics. Can anyone confirm or deny this?