Spyder...
Turn off the caps lock will ya?
As far as track times, theoretically, a stang with 4.10s will have a slightly lower ET in the 1/4 than one with 3.73s. (maybe a tenth or two?)
In the real world, the difference is negligable unless you KNOW how to drive and launch correctly. I usually recommend 3.73s for most daily driven stangs, but some are sold on 4.10s. It's a matter of taste and how you intend on using the car.
A pre-programmed chip won't give you much hp, but it might make your shift points a bit more aggressive...
I wouldn't recommend a custom chip unless you start heavy N/A mods or go forced induction...
As far as cost, by the time you are done paying for all of these bolt-ons (maybe more if you're not doing it yourself), you would be pretty close to having the funds for a head\intake swap.
You can go any route you want, but the downfall of the early modulars are the heads. Replace them, and everything you do after means increased performance....
Case in point:
Show me a stock-headed, blown, 96-98 GT set at 8 lbs. of boost making 450 hp at the crank.... You won't find one because the heads are too restrictive.
You want show, buy a Cold Air kit...
You want go, replace the heads and intake...