Sports suspension was generally a standard fit on early ZTs but replaced with comfort spec as it was found to be a bit harsh.
The build inf on your car says it's a later model so I would say it's comfort suspension it is on my ZT which came off the line 3 days after yours!
Build info on yours if your interested
Vehicle Information
vin RJLLHC4D317939
vin_sequence 317939
off_assembly_date Tuesday, 6th January 2004 @ 09:04:50
model ZT
variant CDTi + (135)
num_doors 4
paint_code LEF
brochure_model_desc ZT D - ENTRY PLUS(2.0 M47 M2)
sales_model_derivative RNQAH
sales_model_derivative_desc MG ZT + 135 CDTi
sequence_number 18271
spec_code L01B
home_export HOME
cicode E4211
country GREAT BRITAIN
exterior_paint XPower Grey
interior_trim Sports Black Leather
engine 2000 Diesel
trimlevel TL 7.1 (M2)
bodytype ZT
manual_auto M
hand_of_drive RHD
model_year 2001
sold_date 2004-02-01 00:00:00
registering_cicode A3756
n09_feature N09A
General Information
This vehicle was the 12,982nd ZT to run off the production line, out of 18,894
This vehicle was the 1,960th ZT CDTi + (135) to be made out of 4,184
This vehicle was the 1,713th ZT in XPower Grey (code: LEF) to be made out of 3,143 XPower Grey ZTs
Hope this helps
Scott