the best 1.6 ecotec engine was based on the lotus designed corsa gsi engine - they put a vxhall intelet manifold and knocked off 20 bhp
i got a vectra 97 1.6 with 195k on the clock and it is still going strong with no taps or rattles - she feels so restricted it is untrue
i have tried the later 1.6 engines and they are pants
try test driving a corsa 1.2 m8 they are gutless as well - the 1.0 3 cylinder has more poke