Who is useing Header extensions?

Well I just order a new set of ceramic coated headers for my Dakota and I am going to have to move my o2 sensor. I see that they make header collectors that have the o2 sensor bung welded on. So I got to looking and see that they also sell header extensions in 12 and 18 inch lengths. I have heard and read that they will add torque and HP. I have never used a set before. So just looking for info to see if anybody on here has used them and did you see a ET improvement etc with them. Also I am unsure which ones to get. I have a 11.1 compression 360 magnum, trick flow heads, comp 580 lift solid lifter cam, indy single plane intake, Holley 800DP, 904 Transmission 8 inch 5600 stall and 4.30 gears. 96 2 wheel drive Dodge Dakota. I hope it doesn't weigh more than 3300 pounds with me in it and ready to race.