Why not gears?! I just got 3.73's put in my '97 and it made a world of a difference. I also haven't seen ANY drop in MPG. This should definitely be his next mod. I'm planning to go to the track (weather permitting) Thursday so I'll let you know what kind of difference in time they made.
If he doesn't want gears, then I'd save some money up and purchase the 99+ heads.
Other good bolt-ons are the Steeda timing adjuster, pullies, and a K&N.
------------------
------------
1997 GT Flowmasters,K&N,3.27 gears
RedSOHC