William Kotzwinkle and Don Winslow
I first heard of these two fine authors years ago on Chris' Picks and have been reading their stuff since.
Especially Kotzwinkle, who has written so many books I keep finding more every time I think I've seen them all. Favorite is Queen of Swords and a recent surprise find is The Fan Man. Maybe it's just me, but I liked Fan Man so much I dropped everything and wrote a similar book myself.
I had read Winslow's A Cool Breeze on the Underground years ago, and again recently, which led me to The Death and Life of Bobby Z which I am throughly enjoying.