for once, i tel u wat it mean...it mean tat ur friend car is
boosting at 1.6bar or pressure to go faster...is also considered
high boost which some may call it...
for rex boost at 1.6 bar is very kong bu liao...1.4bar already very
knn....
so may i ask u a qus, wat model of turbo
he use to get 1.6 bar of booost...he drive wrx or sti...??? his
booost come at wat rpm, end at wat rpm....u sit inside cannot be
dunno mah....tis qus is only drive rex ppl then will know..or
always got sit rex ppl.... 
A tip for u, if u hv to search for the model...its either in VF- or
in TD- .............