What would be the best upgrade for my 105 brakes. I dont run carbon rims.

I just put a set on Kool Stop Eagle 2's on the 105s i have and i am amazed how quick the bike stops.
they look out of place but they work!

Jagwire Sleek Pro's are awesome, but are probably more expensive than the calipers, like about $65 a set F/R but come with two different compounds, lightweight holders, and are incredible improvements over anything Shimano (and others) offer.

I find the Kool Stop Dura-Type Dual Compound replacement brake pads to be about the best I've used. You can order on-line from this link:

http://www.biketiresdirect.com/productdetail.asp?p=KSBDS&tn=10537630