See sig. Stock longblock w/ bolt-ons. Race weight is 3550 w/ driver. 96-98 4v heads are better than 99+ heads when it comes to forced induction(they have more potential when it comes to porting) But for n/a cars you cant beat the tumble port heads on the 99+ cobras. Plus I think the 96-98s had a more aggresive cam duration/lift than the 99+s.

As far as the 99+Gts there are less than a handfull of cars in the 12s(n/a). None in the 11s without a power adder. Yes they are quick but the 4v will pull on the high end since they both have the same torque rating but the cobra having more hp. I would get the 4v its fun leaving the line at 7000rpms!
-Mark