How important is aerodynamics in the 1/4 mile...?

There are a couple of aspects to this question. First, less drag = more speed at the same hp and weight. How much of an effect this has is going to depend a primarily on how fast you are gong. My friend's back-half Camaro hits 150 mph by the end of the eighth mile, so it is obviously a factor in his 1/4 mile trap. It may or may not be in yours.

Second, aerodynamics play an important part in the stability of the car at the big end. Better aerodynamics mean less wandering, less scary stuff.

Third, aerodynamics can play a part in gaining traction, espicially for a RWD car. Once the car is going more than 60 mph or so, a wing can ad considerable downforce.

So, to answer your question: it depends.

as long as your aerodynamics isnt just a wing....yeah it would affect your 1/4
if your going to do a wing......do it right....goto jspamerica.com JSP is #1 rated in every wing contest to see which creates the best downforce
I personally use there new blade wing which is made out of carbon fiber and only weights 6 pounds.....plus gives me the downforce i need...