[Perfectlap]

there is no replacement for displacement.
Unless your Boxster is considerably lighter than his Turbo charged 944 then you've got no chance in a 2.5 or 2.7
A turbo charged 944 is very similar in power and weight to a 2000-2002 BoxsterS. 250 HP on 2.8 tons. The BoxsterS should take that one. Not hard to imagine because the 944's are at least one classs below in local autocross and I regularly match the 300 HP 996's.

In stock trim the 944 is not so impressive.
160 -200 HP(depending on the model) at about 2.8-3.0 tons. A power/weight ratio of .05
a 2.7 Boxster is about 217 HP at about 2.8 tons. A better power/weight ratio of .07 and much better handling to boot.
I think a 2.5 Boxster makes about 180 HP on 2.7 tons so depending on his 944 model it could go either way.