I dont think they are underpowered by any means. In the low range stuff they are good but nowhere as good as the diesel. On road it has ample get up and go.
Compared to most other 4bies they are ok. Small tricks like getting the shift points in the transmission changes, appropriate gearing, induction changes etc all make for better power. Also dont use the overdrive in city traffic on the auto.
Saying that the Unlimited petrol trounced the pesky 2dr oil burners at Crusier park
JTO