I think Luna may be talking about the "lifter" sound most of these motors make. I will agree all the Isuzu V6's I have owned you can hear the valves going up and down at low engine speeds and light acceleration. Never bothered me since I've daily driven some primitive engines (solid valvetrain small block comes to mind lol) but yes you can hear all that going on up there. Also I wouldn't consider 9:1 a "low" compression motor, it's average, and if it was an iron block iron head engine it would be kinda high, the aluminum dissipates the heat alot better so you can run higher compression on pump gas (like 10.3:1 on the 3.5 Z motor, 10.3:1 would not be happy on pump gas with an iron block/iron head engine)