Vader87

I am looking at purchasing this module. I would like to know if anybody has ever used this product on an 87 - 93 GT ? The description claims that up to a 25% horsepower gain can be made. Are there any specs out there of this product being used on the affore mentioned car? Is the approximately $300.00 worth the horsepower gain. I have the normal bolt ons , on my '87 low mileage 92,000 motor. These consist of equal length headers,custom made x-pipe,all 2 1/2" exhaust, underdrive pulleys, ram-air with K&N, 78mm throttlebody & EGR Spacer bored to match, Edelbrock performer intake, 9mm Frpp spark plugwires, 3.27 posi rearend, heavyduty 3 core radiator, World class t-5, & a shortthrow shifter. Any info on this part would greatly be appreciated. Thanks! Victor