ive raced with guys that have z24s that are throwin down in the mid-15's. Lots of mods though. Im running 16.12 in my 2.2L but I've got lots of minor performance upgrades in it. Nothing really expensive like cams, nitrous or turbo/supercharging. I saw a clip of a z24 running in the 14s supercharged, and lots of enginework. For the most part stock 2.2L run in the high 17s low 18s, 2.4s in the high 16s low 17s <a lot depends too, if you have auto or 5spd.>