for a stock 4.6 or 5.0, they coem with 19's. and they use mass air, which reads the actual air going on.
on my jeep which is speed density, came with 23.7's on a 5.9 liter with 245hp/345tq stock. i put on full exhaust, FIPK, TB, heads, cam, intake manifold, and a mopar performance computer...