Something that needs to be addressed is the cars being tuned need to be in good running mechanical/electrical order.

It seems way to common to have cars showup to dyno that a number of things need to be addressed before any tuning can be done.

Things to check:

What gas are you planning on running? Example...I had a Stang show up for a race tune and the thing kept pinging bad...it had less timing than stock when I was done. Ends up the tool was running 86 octane. Tune for 93 octane, run it at least. Wasted alot of my time in the process.

Basic maintainence? Example...car runs like crap when it comes in...plugs are fouled is all to common...even if running rich, swap them out before you get it tuned. Electrical issues are common, fuel pumps dead, fuses blown, etc...if you pay by the hour...this gets costly and even if you pay for unlimited dyno time that does not mean you can take up the shop the whole day because you want to swap every part you can.

These things seem like common sense...but I speak from experience with dyno tuning.