thermal efficency of TC engines can potentially be better than NA engines because they use the recovered exaust energy for some "free" compression work. THis is great for part throttle and continous loading.
However, under agressive use the thermal efficency is lower than NA because they run rich open loop fueling to prevent detonation and High EGTs.
Turbo engines when done appropriately are great for EPA tests and being driven how people should drive to optimize mpg. However, most everybodies foot is a little heavier than optimum.
Captain semi obvious