the number 454 in your vin indicate 280/300 not a 350.
Identification number: WDB1714541F180927 1
The 280 and 300 are actually the same model. In my opinion, I think previous owner has rebadged your car to be a 350.
sorry, you have all the evidence...insurance company, datacard...
2 look was not made in a 350 if I am correct
171473 for the 55's
171445 for the 200K
171442 for the 200K
171454 for the 280 / 300
171458 for the 350
171456 for the 350
P38 SPECIAL MODEL "2LOOK-EDITION"
SLK 300 (known as SLK 280 in some markets) – 3.0 L (2996 cc) 170 kW (231 PS; 228 hp) double overhead cam V6 engine, 0–100 km/h (62 mph) 6.3 seconds, top speed 155 mph. (starting in 2006 model year)
SLK 350 – new 3.5 L (3498 cc) 200 kW (272 PS; 268 hp) double overhead cam V6 engine, 0–100 km/h (62 mph) 5.4 seconds, top speed 155 mph ou 250 km/h(electronically limited).
Member Stinger has a 2010 2look in his 300 also known as a 280
2010 SLK-300 Special Edition (USA "Diamond White Edition", ROW "2LOOK Edition")
he put a Kleemann ecu tune and headers so he is back to where a 350 might be but sounds great!
http://www.slkworld.com/performance-mods-r171/143601-kleeman-tune-headers-down-pipe.html