Is more thrust transformative? Maybe, maybe not, but..............
The USAF A-7s with the higher thrust TF-41 engine (derivative of the RR Spey) performed much better than the early USN A-7s with the TF-30.
The F-14D with the higher thrust F110 engine (and also much more flexible engine) is what made the Super Tomcat super and made it a much better airplane than the earlier version.
The F-8U Crusader 3 with the much higher thrust engine drastically changed the Crusader 2 in many ways.
The A-4SU Super Skyhawk with the higher thrust F404 engine really was "super" compared to the original Skyhawk.
The F-5E (which became the F-20 Tigershark) with the higher thrust engine significantly improved the venerable Tiger.
And the JAS 39 Gripen E with the higher thrust F414 engine is reportedly going to significantly transform the Gripen.
And although in a totally different class, putting much higher thrust CFM-56 engines on the KC-135 truly did transform that big old jet.