jimkaray

With a 93 octane tune they can really bump the timing up and increase the torque. I'm sure all the major tuners set up yield similar results. To 2007StangV6's point regarding stock to 87p to 93r I would add the auto picks up a lot of the initial improvement by wringing the slack out of the autos sloppy shifting in stock form. With the manual you don't get that added plus when going to a custom tune so I would say the step up from 87 to 93 is more on par with the first step up from stock to 87.
also, if you don't have a rear swap bar you should get one and I would add urethane bushings to both front and rear for an inexpensive but effective performance mod.

yourmom6990

Agreed. The difference between my 87 and 93 was night and day.

Nuke

Shorties will provide marginal gains for the cost. I agree with getting a good 93 octane tune. Brenspeed, AM/Bama, VMP write very good tunes. You'll notice more gains with the tune over the shorties.