Ive got a 6.0, Ls3 heads, fast 102, sd tune, 2800ish converter on motor, 620/560 255/266 on a 110 lsa and it breaks up when i get around 2800 all the time. i really cant figure out why. Its alot better once i got it dynoed but not great ill attach the tune. The log shows a bunch of stuff, but that is in there at some point. I was logging to check wot on the street