Sticking with stock air box, Toyota filters.
I put K&N on the Jeep V8 after 25Kmiles, cleaning and re-oiling according to directions, at 50K. Ran it up to around 60K miles.
I started to get problems with throttle lag and cold idle at 60K. The MAF was fouled with oil, and the throttle plate was all gummy. Had to clean up both, and I switched back to a paper filter (Fram). Haven't had the problem since. Over 120K miles now.
I can't objectively comment on dirt bypass and any extra wear on cyclinders, but the Jeep now eats a quart of oil per 1.5K miles.
I put K&N on the Jeep V8 after 25Kmiles, cleaning and re-oiling according to directions, at 50K. Ran it up to around 60K miles.
I started to get problems with throttle lag and cold idle at 60K. The MAF was fouled with oil, and the throttle plate was all gummy. Had to clean up both, and I switched back to a paper filter (Fram). Haven't had the problem since. Over 120K miles now.
I can't objectively comment on dirt bypass and any extra wear on cyclinders, but the Jeep now eats a quart of oil per 1.5K miles.