Yes, before you take your car to be tuned you should do all of those things. Most tuners have a checklist for their customers to do prior to getting tuned. If they dont do this themselves they should expect to pay standard shop labor while these things are checked - or accept responsibility when things go bad beyond the control of the tuner. The reality is that probably 50% or more of the cars that are taken in for tuning are not ready for tuning. The owners know their cars have problems, but they don't tell the tuner, instead they expect the tune to fix everything. And then you have people that don't get why custom tuning is expensive, and whine about paying $xxx.xx for a custom tune done right.

 

Most tuner's make you sign an agreement saying if your car blows up on the dyno or engine failure there not liable for the damages.