Gains from pcmforless with just bolt ons?

Is it worth it with stock engine internals and just bolt ons? What type of a gain might I see and would it affect driveability/mileage? Thanks!

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'97 Z28 M6

Edelbrock Headers, K&N FIPK, Hooker Cat Back, 3" Flowtech Cutout, Pro-5.0 Shifter, SLP Air Foil, 160* Thermostat, LT4KM, !CAGS, !MAF, !TB, !FANS, 245/50/16 Nitto 555R

Best ET 13.510@102.73
1.974 60Ft (Before Cat-Back, Cutout, Pro-5.0)

You might see some... http://web.camaross.com/bb/smile.gif Its good to get a base tune if your a little rich on the big end like Me.. http://web.camaross.com/bb/smile.gif