Your 90 will beat the 98. Hell i beat a 98 with my L at the track and I'm a good 1000 pounds more weight at least and only mods were K&N open cone, FMS 9mm wires, MSD 6A and Blaster TFI coil (my time was a 15.3@90 with 2.3 60 ft.). I used to have a 96 and the early 4.6s suck in the GT's. Yeah the 98 has 225 vs the 215 stock hp of my 96 but they are also heavy and the 4.6 sucks badly for torque performance. Your 90 has the better gear and torque, though if I was you I'd put in some 4.10s if you keep the car. Your car is also lighter and with the auto you won't miss a shift. From what you've told us about your friend, he will miss a shift
. He's running a 2.73 rear gear if he's still stock. My 96, with totally stock and 2.73s ran a 15.4 @ 94 with a 2.4 60ft. But also mine was probably about 200 or so pounds less than that 98 will be (it was a GTS version, weighed a little over 3200 without me in it and 3/4 tank of gas). Though once I put in my 3.73s (I had the T45 5speed) I dropped to a 15.0@92 with a 2.3 60 ft. My bet is you'll take him pretty good.