[Formulajones]

Used to be a lot of guys doing mail order tunes back when I was fooling with LS stuff. Like JLmounce mentioned, with most of those cars being so equal it seemed to work well enough at the time. I can't even imagine a mail order tune on a 60 year old classic car that has 100 different variables changed from the next classic car, and so on. I would think you'd really have to be present and live for things to be spot on. It really is specific to each car. Most likely you would be mailing datalogs back and forth along with your tune while he made small tweaks to try. It could turn into a pretty long process.

As far as target AFR's you've set verses someone else's tune, more likely than not the new tune would have it's own set of target AFR's with it's own learn and fuel trim limits set. The question would be "Is that going to be right for your engine?"

As JL mentioned, once you have a good base fuel table nailed down it's usually best to dummy down the learn feature and just leave the closed loop comp (short term correction) active to a reasonable amount so it's able to make small fuel changes for changing conditions without making big changes to the learn table (long term fuel)

As an example, you can pick certain areas of the fuel curve to allow closed loop compensation to make those small adjustments at any amount you desire. For instance I tend to leave it at 50% adding fuel only in the WOT areas like 80 KPA and above but not able to pull out fuel, maybe 10%, while the rest of the table might be 10% + or -

I do this because I've already had a fuel pump failure that was getting weak. At WOT fuel pressure was dropping dangerously low, but the Sniper was compensating trying to add as much fuel as it could. Dad noticed fuel pressure low as I set up the Sniper to flash yellow below a certain PSI. Thankfully the close loop comp added the necessary fuel to at least try to keep it at the commanded 12.8 AFR. This at least kept the engine safe at WOT but didn't corrupt the learn table because I had the learn turned down.
If closed loop comp would have been turned way down in those areas, the engine would have went dangerously lean and I couldn't be sure dad would have seen it in time before some sort of damage occurred.

This type of tuning or thought process can also be beneficial when the 02 sensor dies. Also always a good idea, once you have a good base fuel table, to have an open loop tune saved on the SD card when you suspect you're having an 02 issue. You can at least drive the car back home that way.