david
just about all automobile manufacturers save money by using wire that is too small a gauge.
relays use a larger gauge wire and are hooked up directly to the battery. you get all the juice you can, no voltage drop.
they do make a difference.
what kind/type of bulbs are you using? [for the 202]
a premium bulb [+30 or +50] would help. you can also consider something a bit hotter than standard because of the glass lenses.
daniel stern sells relays.
http://www.danielsternlighting.com/tech/relays/relays.html
you could upgrade the sl oem factory hid.
peter