Are my XP formulas (or the wiki's) off?

[tristantio]

So - since hitting level 58 I've hunted exclusively on Dragoon Szorn (level 45 mob) in Lesser Faydark solo as an Iksar Necromancer (wiki states 32% penalty, 10% class, 20% race).

At around kill number 550 (I believe it was actually 547) I hit level 59.

I just hit my 1200th kill on him last night (currently I have one full yellow to go till 60).

However, the wiki lists these formulas:

XP for level 58: 41333000
XP for level 59: 64689900

Given the XP for a mob of dark blue con or higher is supposed to be L^2 * ZEM, we can plug in the following to see how many kills should have taken me from 58 to 59:

(PENALTY * BASE 58 XP) / (LVL * LVL * ZEM)
(1.32 * 41333000) / (45 * 45 * 75) = 359.2399

Due to the pet's range, I don't have definite proof that all 550 kills were 100% me out damaging the pet, but I have a pretty good feeling it was (I parsed quite a few, pet never out damaged me and I use the exact same spell rotation every kill).

Question - why were the extra 200 kills needed? What am I missing? Or are the wiki formulas off for some portion of my testing?

Now, on to level 59 - having just hit kill #1200, that means I have 650 kills in level 59 of this mob (I'm counting up the kill messagse in my /log file).

Plugging in the same XP formula:

(1.32 * 64689900) / (45 * 45 * 75) = 562.2430

So...having exceeded 650 kills, why do I still have a full yellow to complete? (we can safely assume another 160 kills).