what should i expect from a custom tune that i will be getting on friday? WEll this friday the 9th i shall be getting a custom tune done on my truck. My truck is a chevy silverado 5.3L with headers intake and full exhaust. I had a throttle body spacer on but the guy at synergymotor sports recommend it to take it off before i go. Also my ? is how much hp should i gain? and would it be worth the money im paying for the custom tuine