I figure $500.00 plus for a custom performance tune, it's all labor, scan/tuning software cost recovery and dyno time. Would include tuning on a dyno for WOT and then road tuning and testing for normal drivability. Should include re-tunes for problems that come up. Basically depends on what your expectations are. You want it drivable, or do you want screeching tires and neck snapping shifts. Better mileage on cheaper gas or performance and fuel cost is not a factor. My '94 Camaro Z28 is tuned to chirp in 1st to 3rd shifts, hard, fast shifts, runs on $$$ 93 obtain only and eats through a set of $1200.00 performance tires in less than 20K miles. My '07 Envoy is tuned way different by LimeSwap. Peppy, firm shifts , but not jerkey, enters WOT earlier when I need it. timing setup for 87 octane. Turned off a problematic DTC. Last round trip Atlanta to St Louis got 21.0 MPG both ways (1200 total miles), close to 400 miles per fillup. As far as mods go a tune is the cheapest dollar to performance ratio around. I used the PCM loaner option with LimeSwap, no down time.. Only cost an extra $6.00 to send back the loaner.. I really wanted to buy HP Tuners and DIY, but the $500.00 software/cable cost for a stock 4.2 setup seemed high..