no, i wasn't aware the 6.4 had a fully forged bottom end. i know the 6.1's would need a considerable amount of upgrades before going too much over 500 WHP (Crank, Pistons, Push-Rods, etc...). i'm looking at spending close to 10k on a SC in the very near future. unfortunately, with the stock configuration i won't be able to go much over 10 Lbs because of those non-forged parts. and, while (just under) 10k is doable after a deployment, 15k (to upgrade the afore mentioned components so i can add more boost) is not doable.
question: if i can manage 500 HP (at the wheels) with 10 PSI boost, is it recommended to upgrade to a 3" exhaust? or would the stock 2.75 still be the best option? i know 1-2 folks with a SC'ed stock 6.1 (8-10 lbs)....did you keep the stock exhuast?