Six speed '06 Allison

My dad just bought a '06 2500hd w/ the lbz and 6 spd allison. We have been looking at getting a tune or programmer to add about 65 hp or so. I have been looking around and have seen where adding too much torque to the allison is a bad idea so I feel like 65 should be plenty. I have also noticed that it seems like the ones that fail the most with added power are the earlier allisons, is this accurate? I also read somewhere that the newer allisons will hold additional power better than the older ones but I haven't found enough information to fully support that. Are the fifth gear clutch packs still a weak point? Is the torque converter any stronger? Whatever tuner/programmer we get is going to defuel between shifts, I think that will go a long way in making the stock tranny last.

Thanks,
Matt

PS: I should also mention that this truck has 285's on it... that will affect the torque load on the tranny.

Running 285s just means you could be using more engine torque while towing. If you add power that pushes the torque limit of the Allison, then yes, 285s could affect the transmission over time. On the other hand, if you're below the torque limit with a power adder, it might not make as much of a difference.

Jim