This transit custom came to us already tuned (very poorly!). It was tuned by a mobile remapping company that went to the owners house. He was there for the whole of half an hour flashing his generic file onto the van, without even taking it for a drive. If they had, they would have noticed how poor the power delivery really was!
It took forever in the day for the power to come in, then it was all over by 2000 rpm.
We put this van back to stock before tuning it, it was a little down on power but with 125k on the clock this is justifiable.
Even after, it was down around 20hp from what we would have expected, we did advise the customer to use premium fuel in it as it makes all the difference.