What do stock '89 5.0L run?

Agree with these guys. Cars run slower at higher altitude. didn't say if it was stick or auto, but i would imagion with a good driver, that might make a .1-.3 difference. I doubt you'll get much lower than 15.4 tho. sticky tires and gears would get 14's.
 
I ran a flat 15.0 in the 1/4 with my prior 5spd notchback at 800 feet elevation (KCIR), no powershifting. Only mods were an off-road H-pipe and Dronemaster cat-back (with many rust holes), and some VERY hard-as-rocks, un-hooky tires that netted me crappy 60' times ... something like 2.1 or 2.2.

Now, add in more weight for your car being a hatchback, presumably bone stock (if there is such a thing as a bone stock '89 Mustang left in the world), and that suffocating 5000 feet of altitude ... I'm betting at least mid 16's (which is about what my '94 Crown Vic Interceptor last ran).

Do we win cookies for betting closest without going under? :D
 
I ran a 14.5 with my car AOD at 94 mph. The car at the time had 123K on it with Long tubes-Hpipe, flows, BBK cold air intake, pullies, chip and 3:73's. So for a bone stock stang to be in the 14's I don't see it! Just my opinion.
 
You are looking at mid to high 15s with good driving.
To get in the 14s you defiantly need slicks, gears, and couple bolt on i.e.: exhaust, k&n, pulleys.
With my car i ran 15.7 on street tires with just the h-pipe. I could have got 15.5 on a perfect run.

Last time I went to the track I went 15.04 on slicks and the mods in my sig. With a little more practice and my 25# N20 bottle out of the trunk I guarantee I could get a 14.9x
All of my runs were naturally aspirated as well. On my 125 shot I should be around a 13.8
 
ran 15.06 at 93MPH without my gears when I was in Hawaii and that was spinning everywhere. If I launched better I could have hit atleast a 14.99. All I think I had was my exhaust and timing to 14*. Maybe the altitude makes a big difference but I don't see 14's being hard to get.