go 01 if your looking at new edge cobra.... 01 has the nicer interior setup and the velvet inserts in the leather seats where the 99 has full leather seats and a lack of a 6 disk cd changer... i have an 01 cobra with full length headers, prochamber, flowmasters, lowered with 315-35/17 tires, and i absolutely LOVE it... and for the cost difference between the 01 and 03, you can build one hell of a fast 01 that will drop the cheese of an unexpecting 03-04 that is unmoded...

if you go the 99 route make sure it has the fix... which is noticable by a dot on the driver side front corner of your intake manifold with a green dot representing acid dipped and a blue dot if your intake was extrude honed.