Well got the new 5.3 i put in the old SLO Truck today. Allen worked his magic again. Truck is running really strong. A/F is spot on. The 5.3 is feeling better than 4.8 for sure. Still breaking them loose at 40-45mph. Track and dyno number soon to follow. I would also like to thank Nelson Performance for providing such great customer support and a get it done attitude. THANKS AGAIN