Engine port explanations please

[tellor]

Hi all,

I'm thinking of a new engine and am interested in a particular one but they have 3 different off road types;


a 5 port ----appears to be high torque ( got that)
a 7 port ----appears to be high speed ( got that)
and a 5 + 2 port ????? bit of both??



Can someone explain what the differences are and am I likely to notice the difference between the cheapest and dearest one?


cheers