any one had much success tuning a stock 05 5.3 pick up? i went up to 12.8 a/f and it lost hp, left the a/f at 10.5 ive got up to 28 degrees times and no kr is were i made about 6 more hp and ive played around with all a/f and timing settings and still cant get this thing to make any more power.. were going to put some better exhaust on it today thinking the stock muffer is holding it up
any suggestions??

 

Which motor is it? Is there a "T" or a "B" in the VIN?
Let us know on the Exhaust change.