@henkkeumus
think youve got a couple of the dates a bit wrong, plus the 8p1 is an 8p2, and the s3/rs3 models arent right as s3 came in 8p2 and 8p3 style, rs3 came in 8p3 only.
8p1 (2003-2004)
8p2 (2005-2008)
8p2 s3
8p3 (2008-2013)
the trims etc arent important as you can still swap bumpers on an 8p2 SE to Sline, but not from an 8p2 to 8p3.
the 8p1/2/3 thing came about because of that reason i think (before my time) as people with 8p1 wanted to change to 8p2/8p3 and wanted to simply change bumpers not realising it was wings/bonnets etc too.