its always been the way of nissan to qoute the (gentlemens agreement figure) ie 276bhp on the 32, 33, 34's but when cars have been tested indipendntly some have come back at nearer 320bhp. the same thing happened with the 35. nissan said it was only 480bhp and indipendant test came back as high as 510 if my memory serves me right.
if you use 0-60, 0-100 & 1/4 Mile Calculator :: TorqueStats Modified
the figures come back about right though.
having only ever driven stage 1 gtrs i cant comment on the 0-60 of a standard cars. but using the same website and using my stage 1 R33GTR's stats it comes back almost spot on so it cant be far out at 5.6 for a stock car can it?