You can definitely improve the suspension quite a bit within your budget.
I would suggest the following..
Most Important:
[ul][*]Shocks & Struts - a good set of aftermarket shocks & struts. The 03-04 Cobra's had Bilstein from the factory, but the 99-01 did not. So upgrading to a good set of
Bilstein Shocks & Struts will be a nice option for you.[*]Lowering Springs - The
H&R Sport Springs are a popular choice for 99-01 IRS owners. They will lower the car about 1.5 inches, and makenoticeable improvement in handling.[*]
Caster / Camber plates - after lowering, you will want CC plates to help align the car properly.[/ul]
Also Recommended:
[ul][*]
Spring isolators[*]IRS control arm, subframe, and differential bushings (to revamp the IRS and replace worn OEM bushings) -
IRS Bushing Selection[/ul]
Also, if you wanted a "no fuss" solution, and you did not want to customize anything... Maximum Motorsports has a nice packaged called the "Starter Box", which includes many of the items I'm recommending.
http://www.stangsuspension.com/store...?idproduct=176
Sincerely,