My first custom tune was a Diablew tune on my 2013 Black Diamond Avalanche with a used diablo tuner off flea bay; cost me about $350 total and it was well worth it; had greatly improved drivability that was most apparent when I took off the tune to drive it in for the trade - I couldn't believe how bad the stock slurped. The trade is a 2018 Suburban LT 4x4 5.3, and though I want to try a BB tune, they have crept up to around $700 these days. I'm sure they are great, but there is only so much a tune can do, and 7 hundy is most of what my new Corsa cost (it alone is fantastic). Instead, I opted for the diablosport tuner to again let Lew tune after I got my new exhaust installed, and flea bay has tuners. Much to my chagrin, I picked up a refurb factory diablosport for cheap, and put on the "Jammer CAI" tune that was on the tuner. Apparently, its a 91 tune specifically for that brand CAI, but since I have a Airaid Jr and a new Corsa sport, I figured an increased airflow tune would apply until I got a few tanks of 93 through the truck. I added 11% throttle increase plus AFM off to that tune and kept everything else the same. Its sweet. I'm not sure if I got lucky or what, but this thing breaks loose. Could be the Corsa effect (which is, BTW, the best exhaust I have ever owned), but man I am one happy mofo right now... Update. Lost about 3mpg with that no afm 91 tune. Went to 93 diablo tune with afm, and got it all back, plus it seems to run a little bit better...