Ok your cousin's car has a 5.7s 0to60 and a 14.2s 1/4. But that was back in 1995. Probably isn't quite that anymore, even if he can drive.
The TB is not going to do anything for you until you get FI, and even with those other mods, your rwhp/tq won't even be at the advertised hp/tq levels. But those 4.10's will help a lot. You should look into an aluminum driveshaft and control arms. With some nice lower control arms and an upper CA, and a DS and those other mods you've mentioned, you will more that likely beat him.
Give this site a look:
http://www.supersixmotorsports.com/pdf/SSM200840SOHCCatRev1HeadsCams.pdf
Look at this thread for an idea of what you need to be at the level you want:
http://www.moddedmustangs.com/forums/4-0l-2005/101712-1-4-times-4-0l-v6s.html
The TB is not going to do anything for you until you get FI, and even with those other mods, your rwhp/tq won't even be at the advertised hp/tq levels. But those 4.10's will help a lot. You should look into an aluminum driveshaft and control arms. With some nice lower control arms and an upper CA, and a DS and those other mods you've mentioned, you will more that likely beat him.
Give this site a look:
http://www.supersixmotorsports.com/pdf/SSM200840SOHCCatRev1HeadsCams.pdf
Look at this thread for an idea of what you need to be at the level you want:
http://www.moddedmustangs.com/forums/4-0l-2005/101712-1-4-times-4-0l-v6s.html