Factory Tranny w/tuned LML Duramax?

I am about to order a 2012 Duramax and intend to buy the H&S Performance Black Maxx, DEF delete, and 5" exhaust kit but a buddy is telling me I'll take out the tranny before long doing that. I'm not doing any towing, just excessive 2 lane passing etc. Anyone tried that who can tell me how it's working out for them? ...My other alternative will be to buy a Dodge with the cummins and thier 6 speed automatic...

Eventually it will hurt the trans, how long depends on too many factors to give any real answer.

It's worth mentioning that putting a tune in a new truck is a bad idea if you want any powertrain warranty coverage. You can try to hide it but they have plenty of boobie traps to find it, and if they find you hiding it you will have complete warranty block. Just some things to think about, I have seen some very unfortunate souls denied coverage on failures on parts which I have seen similar failures on stock trucks.
There are a surprisingly large number of diesel warranty labor operation that require Gm approval before replacement and the first thing they ask for is screenshots of the ECM cals and a couple screens of data.

Mike l. says they are not going to take to big power. He is working on kits for it though.

my lml is staying stock for a while, but i know the stock allisons are only able to take 90hp over stock before they start to limp a bunch. for some reason my lly's stock tranny lasted me quite a while with my efi live 200hp tune before i swaped it out, but i didn't really beat on it too much until i had the funds to upgrade it. you'd be safe running a 90hp tune for quite a while as long as you treat it right.

from what i have heard the new allisons are pretty much just built enough to handle a little more then what the lml can throw at it but thats all i have heard about them i have yet to see one with a tune on it so it just what i have been told. but i agree if you plan on having warranty work done on it you dont want to put a tune on it or mess with the exhaust system on it it voids your powertrain warranty