I had long discussions with the guys at HHP about what to do to get a nice bit of performance boost out of the 6.1 in my 2006 Charger SRT but still keep it able to use daily on the street comfortably. In the end, I put in a 3.92 Getrag LSD and it is awesome! Pulls the power band in nice and tight and provides nearly instant acceleration. I also added a 93 octane tune from DiabloSport to optimize A/F across the full RPM range.