Piper Cherokee 140 vs Cruiser

I've noticed the performance of the PA-28 Cruiser is much less than the other Cherokees. Can anyone elaborate? Its ceiling is 10,970 as opposed to 14,300, its cruise speed is 110 knts rather than 117 knts, and the useful load is 875 as opposed to 913. The HP on both is 150. But amazingly, the Cruiser has a top speed of 124 as opposed to 123. The empty weight is only 53 pounds greater on the Cruiser. I'd love to hear any explanations or possible mods that will bring up the cruise speed, ceiling, and useful load of the cruiser.

------------------
Todd