It's peak torque and how it's delivered that are the limiting factors rather than power output.
Making a progressively-delivered 200bhp with a high-revving 1600cc 16v lump will be much kinder to the transmission than a 200bhp 1.3 8v with a G60-lader bolted to it. Virtually all gearbox failures will occur on transient events - going from light load to full/high load. Those transients are much harsher on cars that deliver the instant torque hit of a G-lader.
