S Line was only offically offered for the 1.8T run out model (190BHP). Cosmetically apart from the bumpers and door blades, it had RS6 style 18" alloys. and some interior changes including door sill plates embossed 'S Line' and a perforated leather steering wheel with 'S Line' badge and perforated leather gear knob.
The B6 Sport models that came out in 2004 where offered with the quattro GmbH kit as a no cost option which consisted of front and rear bumper and door blades akin to the 'S Line'. We all just refer to it as S Line kit as it's effectively the same thing, the diesel's just have hidden exhausts.
So if your car is a 2004 model the body kit will be factory fitted if it's prior to this time it could have been retrofitted. What year is your car Scott B?