The springs I removed from my 2005 Roadster when I fitted steering bearings were Eibach 'Plus 8' springs in pale blue.

From their website:

EIBACH UK
25 Swannington Rd Broughton Astley
LE9 6TU
Leicestershire, England LE9 6TU
ENGLAND
EMAIL: sales@eibach.co.uk
(44) 1455-286524 Phone - (44) 1455-285853 Fax

DaveW
'05 Red Roadster S1
'16 Yellow (Not the only) Narrow AR GDI Plus 4