The only time you would notice a difference is after sitting for extended periods of time (days/weeks) on first cold startup. The filters have anti drainback valves so should be full. The smaller z160 was used to clear the radiator hose in the later commodores.
No problem with either filter, and there will be no difference in pressure between the 2. Advantage of the larger z30 is increased filtration area (and consequently less chance of imploding the filter if oiling mods done on the v8’s).
I agree the increased filtration area is great. z30 for the win there.
However the anti drainback valves doesn't negate the larger surface area of the filter that needs to be pressurized, yes the oil filter is full but when running it stretches lightly due to oil pressure, the larger the filter the more it stretches till it reaches pressure, I could literally watch effect on same engine running Z160 vs Z30, ca stopped for a few minutes, the z30 could take twice as long for the pressure to reach.
I could literally see the oil reaching the rockers, top of engine with a Z160 (obviously when working on engine and rocker covers of). And that was warm starting.
I also heard the engine settle much quicker with the Z160 when stop start between runs at the track, motor carna and carna cross type events.
Lots of short stop start Z160, Highway or medium long drives Z30
It worked for me anyway.
P.S.
I tried because of advice I received in club motorsport for the old inline 6.