Found a pretty cool site with all of the 03 and 04 production numbers:
Here are the coupes
2004 Cobra COUPES BY COLOR
Color Name Body Style Units Sold
Screaming Yellow Coupes 299
Competition Orange Coupes 281
White Coupes 316
Torch Red Coupes 477
RedFire Coupes 509
Mysti-Chrome Coupes 515
Silver Metallic Coupes 551
Black Coupes 820
Total Coupes: 3,768
Here are the Convertibles
2004 Cobra Convertibles BY COLOR
Screaming Yellow Convertibles 167
Competition Orange Convertibles 72
White Convertibles 128
Torch Red Convertibles 167
RedFire Convertibles 209
Silver Metallic Convertibles 266
Black Convertibles 392
Mystic-Chrome Convertibles 495
Total Convertibles: 1,896
Based on those, the comp orange is the rarest Cobra conv. produced. It wasn't a color in 03. I guess I stumbled across the rarest convertible... wow....
Here is the website:
http://www.yellowmustangregistry.com/Production04Cobra.html
The numbers seem the same as what the SVT rep said.