the mustangs have a notchy rubbery bent shifter. dont like the way theyre positioned at all.
you can tell him this.
my 98 z28 Ls1/A4 pretty much stock (lid and catback) put down mid 13's on street tires with 94k miles on the clock. a buddy has a 2001 mustang, 5 speed with the same mods running mid 14's with the same mileage on the clock.
thats a good year GT vs a crap year z28 (first year model).
just tell him your point of view of the bang for your buck and let him make his own decision. theres like 3 gt mustangs on craigslist right now trying to trade for a ls motor car. you can always show him his future