I was on vacation in cali this weekend (went to the nascar race) and my aunt's husband let me drive is 03 z06 with a vortec intake and borla exhaust. That car is fassssssssttt. I didn't like the interior and it didn't sound as good as the 04gt, but it was soo much faster.
.. Think about it though, if you put that 40 grand into your mustang, it would be the fastest, best looking, coolest mustang in your entire city for sure! 
or are you too busy with having Tim build you ANOTHER 600+rwhp car?
Funny you mention another car being built though......... 