well this is an older thread but i wanted to comment..
yes the Duramax is fast in stock form and with a lil tuning it can be insane but it has a few down falls as well..the stock 5SP Ally doesnt like alot of extra HP but the 6SP Ally doesnt seem to mind 450-500HP..i have seen quite a few newer Duramaxs with tuning only and a few drivetrain upgrades run mid 12's then shoot a lil juice and hit low low 12's and thats on a CC SB truck..
in the end i wont bash the PowerStroke,we have a few ofem and they have been a great truck for us..