20mm spacers make 166 wheels more aggresive, because of the design, offsets and all.

Not that much on other wheels I guess

 

The best view for the 20mm spacers is from behind. The tires look pretty massive, and your car looks pretty aggressive.

Without the spacers, the wheels look really inset and tiny. A 19" wheel looks like a 16" wheel (mostly due to the low profile tires).

 

agree that without the spacers, the wheels look really inset. looks good where the rear wheels are now placed. spacers do make a cosmetic difference