240awkw out of a GTR is just a matter of 1 bar boost, computer and exhaust. Maybe $3K and you lose none of the bottom end. Sure its a bit doughy under 3,000 rpm but its not enough to warrant your above post.
You can also reduce the unsrung weight of GTR by using light weight alloy wheels just as you have done.
It sounds like your saying just because GTR's carry a bit of extra weight people shouldn't waste time with them unless they are going to stroke the engine? I maybe wrong but can not make out much else from your post.
I love so many different makes, models of various cars of all ages so I am not just GTR biased.