An old fashioned remap/ ecu tune?
Very good

The old chips out of the ECU (behind the windscreen wiper) of my 2000 MK4 Golf GTi - first ever tuning I ever did and it was done at GTi International in 2001 with my car only having 2000 miles on the clock

The company that did the work was Upsolute (Austrian)
Funny thing is they never made it big in the UK, but their work was really good.