-it depends on how much you want to spend, and how well you want it to handle.
-bilstein/koni are the best. yuo will pay for these more than the others listed below.
-but tokico, kyb, and alike are good too.
example
Starter Box, 1994-98 Mustang & 99-04 GT @ Maximum Motorsports (
Maximum Motorsports :: The Leader In Mustang Performance Suspension)
MM Road & Track Springs
MM Caster/Camber Plates (select Black or Chrome finish)
MM Urethane Pinion Snubber
Bilstein Struts and Shocks
Front and Rear Spring Isolators
$1118.48 Part #: SBX-3
or
Sport Box for 1994-95 Mustang HT
MM Strut Tower Brace (select Black or Chrome finish)
MM 4-Point K-Member Brace
MM Standard Subrame Connectors (bare steel)
MM Panhard Bar with Aluminum Rod
H&R Sport Springs
Tokico Premium Performance Front Struts
Tokico Premium Performance Rear Shocks
MM Caster/Camber Plates (select Black or Chrome finish)
MM Urethane Pinion Snubber
Urethane Front Spring Isolators
Urethane Rear Spring Isolators
Urethane Steering-Rack Bushings
Urethane Front Swaybar Bushings
Front Swaybar End-link Bushing Kit
$1448.85 Part #: SB-4
or
Mustang Suspension Packages
Suspension Packages @ Stang Mods.Com
$460-660 You can get shocks, Struts, & Springs
You'll maximize the use of being lowered by getting those such parts when you lower the car. My coworker uses Saleen Springs on his stock shocks and struts on his 94 5.0, and has yet to have a problem. Figure thats about an inch drop with those springs.