i just finished installing my lt yesterday and the ses light came on. i hooked up my scanner and found 4 codes where set. The codes where p0140,p0160, p1133 and p1153. The all have to deal with the front 02's (insufficent switching activity). I drove the car open headers home until i get the exhaust done. The headers are slp and i removed the egr and air. I had the car tuned to remove the egr and air pump codes and i think i removed all the rear o2 sensor codes. I think the fact that the o2 sensors are so close to the exit of the header that they are causeing the car to set these codes? The LTFT is in the 20's

and way out of wack numbers for the o2 sensors. Will putting my dual muffler set up fix these codes or will i need to build a new tune to get rid of this problem(so i build can build a tune to get a full benefit of the exhaust). I also just replaced the o2's, spark plugs,and spark plug wires about 4,000 miles ago. Thanks for any help