Someone (don't recall at this moment) that had made a tune on his chip put his dyno sheet on V8SHO. When you compare the curves stock and after you can see an average 5-8 hp gain but for what is worth (400$)... (I will find the link later as I'm not at my house now.)
I have the impression you skipped some usefull steps, maybe it's not the case but before doing this and starting "driving it like you stole it":
Verif.:
-Weld the cam if isn't made, if it's made, check them anyway, some welders did this very badly
-If CEL light is on, try to repair bad parts causing check engine codes, because almost all is linked together on this car, even if it's a 97...
-Put good tires on it (at least medium grade with V shaped surface against water)
- Check the state of the suspension (watching how rebounds you have at each wheel), espacially the rear, the spring can broke easely there (my 2 were broken)
- Watch for misfires at idle (park and engaged) coils handle a lot of heat (when I bought mine, the originals ones seems still there and they were all cracked), you will have some performance gain with news if you have misfire (when you have no misfire, this motor surprisinly quiet, no vibration at a point that I think sometime on a redlight that my motor stalled)
Modif.:
- Rear brakes bias bypass (You will see the difference, probably one of the best security upgrades), this thing is clogging with time and you finish with almost no brake on rear wheels, by the way secure all 4 wheels, rear cylinders jams easely in salted area (hp gain isn't so good without brakes)
-Saxectomy (removing all intake parts in fender, saxocone and intake silencer)
-3rd cat delete (will cost a lot less for the same result in hp : around 7, this thing can also be clogged)
- Think about replacing the rear springs or at least putting a bigger rear sway bar to eliminate some bodyroll this car, with a good suspension, can handle curves like a Porsche, better than many Mustangs (talk about that with M. Newberg)
Good luck,
If you need infos or trick to find parts (in Canada), pm me.