[2010abmss]

Most manual ZL1's dyno around 480-500 stock. Do you not even have a CAI? That alone will net you 30+- HP. Also get you a ported TB $150 for easy HP. 515 sounds really low for a 2.5 pulley, that's 18% overdriven. I would expect at least 550-575. I know LT's are leaving a little on the table but not too much. To me it sounds like that tune is not right. If you are somewhat mechanically inclined you could have easily installed everything and just had a tune done and saved a good bit of money.