But your super car performance base model R34 GTR would not hold the same value as a ztune, not even close.
Clear examples going through the for sale section here, cars with 100K+ work, sell for less than 100K.
I should add that a lot of these cars that are built, are faster than the ztune in at least one way or another.
Most of the people who can afford a ztune, aren't buying it to be able to drive it around the track.
Well thats what I believe.