Pull-ups is a stricter exercise for lat development, alot harder to cheat when you're hanging from a bar even if you're swinging around uncontrollably to get another rep out. If you watch carefully on the lat pull down machine, most lean back on the heavier weights defeating the purpose and it becoming more as a modified seated pully row.
Try this for a great pump that will hurt like a mother if you aren't strong enough to wear weight around your waist or a dumbell between your legs during the pull up. If you find you can only pull your own weight up 4-6 reps (and using wrist wraps), drop to the ground and start the clock. Wait 45 seconds and knock out 2-3 more reps. Do this for 4-6 sets..even if you only get 2 reps out on the first phase of the last set. You'll find your strength go up fast on this and you'll be using added weight in no time.
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