ORIGINAL: Mystic_Eats_Rice

The 99 cobras do indeed have 320 hp/317 ft lbs if the have been fixed by Ford. The 99 was the first year the Cobra got IRS and it has 3:27 gears in the rearend, not the 3:73's. It also came w/ the new tumble port cylinder head instead of the old "B" heads or butterfly port. It has an aluminum block and heads, forged steel crank and 57mm twin bore throttle body. The camshafts are higher-lift longer duration units than those used on the 96-98 cobras. 0-60 5.5 sec and quarter mile in 13.8 at 102 w/ good driver. Another change was that the 99 had the same sized brakes as the 96-98, but the front rotors were made by Brembo in 99. Oh, and it also had traction control. As far as the 99 compared to 96-98 I think the earlier models had a better body style and are almost as fast stock, 13.9 @101.9 w/ good driver so I would go w/ a 96-98. The IRS is a pain in the *** on new models (bad wheel hop) and will have to be strengthened or changed to live axle if he get real crazy w power. If he likes the body of 99+, he should consider a supercharged 03 or 04, they cost more but definitely give more in return. There is my novel, hope it helps.
Adam