I could be wrong, but the last year of the 420A motor in the Eclipse was '99, not 2000... Could you have meant '99? If you did then, there is no difference between the 2.

DoN
'99 GS Sports Edition
Star Stage 2, CFDF Clutch
Greddy Manual Boost Controller
Greddy BOV and EVO Exhaust
Greddy TT and shift knob
AF/X Underdrive Pulley
AEM Big Brake Kit
B&M Edge Short Shifter
Eibach Sportlines with Tokiko Blues

'99 Eclipse GS Sports Edition
Star Stage 2
Greddy EVO Exhuast
AEM Big Brakes
Greddy Type S BOV
Pioneer DEH-P7200
Bazooka EL1500 running 2 MTX 10" Subs
Fosgate Separates throughout