Karnut. Seriously I cant really just put a number on it because of the amount of responce you get in your throttle!!! If you put it on a dyno the peak numbers will or could have up to 25-30 gains but the numbers across the board are a substantial increase because of trq mangnmt. Forgetting about dyno numbers all together you will lose that lazy pedal feeling and if you drive aggressive at all you will se a increase in MPG under a load and aggressive driving. These trucks are like 10.0 rich on AFR when under heavy throttle and into your power enrichment table because they poor the fuel in. So after a good tune that leans it out to like 12.8 or so you will not use as much gas during spirited driving. A good custom tune is by far the best mod for the money IMOP. Seat of the pants feel is unreal. Just imagine a tune in a handheld that works on every truck thats your trucks model being a 50 out of a 100 score tune. Then the custom tune if done correctly is the 100% tune thats only for your truck. If a handheld can be felt with the butt meter then imagine what a custom tune feels like. Crisp shifts, holding gear longer, no more hunting gears, all your power moves to throttle tip in!! Instant power not held back till middle of RPMs then pulled out again before you shift and then walked back in again to do the same on the next shift. Hope that helps. Get on youtube and look at some new camaros before and after tune dyno numbers and watch the trq curves sometimes its possible to see 80ftlbs of trq gain down low in RPMs because of throttle response. Dont look at peak numbers look at whole curves.