As Dave suggested I do set up owner laptops with cables so they are ready to go. Also do live tuning with an emulater and remote desktop connection tuning via wireless internet. Also have one as a loaner but it is out right now.

When I do them by mail first I send a starter chip. To do anymore I have to have data log or it's all a guess and wasted time and mail, not to mention not tuned right.

Also he can send you a chip without wating for a return, yes there should be a clause that they all have to be returned in the end. I know why, it's because scam chips has been exposed! We have many! But why make you suffer the wait. Just mail one..... but without data why bother?

Headers can cause some false knock, most stock 1227747 5.7L engines will have soame false Knock WOT anyway. Even worse and possibly KILLER with your timing curve if the ESC test is left on! It adds 11 degrees timing as a Knock Sensor test at WOT, if no respnse it adds 22 degrees! Just turning off the error code does not turn off the test!

You can also have Knock long before you can hear it!

Your scenario of 38 degrees advance with timing light scares me! What happens if PE spark is added (another 5 degrees) which you can not do while under the hood with a timing light? What about decleleration spark? For instance one bin had 39 degrees in 20 MAP column, you moved your distributor 12 degrees, now you have 51 degrees advance during decel and it's firing the wrong cylinder!

OK now say spark is stock at 16 at idle, you added 12 so now it's 28, then start up spark is added and it's 36!

Besides 38 degrees is to much advance in a daily driver light car and who knows the quality of fuel, and stupid in your heavy big tire beast. Even if that wasn't a consideration I would never run that much advance with out a knock sensor. Not even close if by mail, little more hands on. I'm a wimp on the safe side but I have yet to hurt a motor. Screw the last 15 HP unless your on a dyno, then still back it off for a daily driver.

Pull your spark plugs and use a magnifying glass to look for specs (melted metal) on spark plugs.