[foreman00081]

for big power you have to build the tranny, shift kits alone are not enough, new clutches and a new torque converter are a must. the allison is hands down the best tranny going now but they are not made to hold more than maybe 100 extra horses over stock or they will most likely limp and once they limp it will do it easier each time after. i had my tranny built by Eric Merchant, one of the top allison builders in the country so now i can probably go to about 800 HP if i wanted to. now im not planning on going that far, im at 372HP at the wheels now, 679TQ and im looking to get to about 500RWHP. after 500 or so HP then you need to start looking at engine internals and im not going that far cause then your talking serious coin and i dont have the time or money to get that far into it. heck the tranny alone cost me almost $4k. so if youre planning on that much power you better have some deep pockets, not trying to discourage you, just letting ya know, it gets expensive quick and its more addicting than crack laced with crystal meth. but like scottsdale said, for more info than youll ever want to read about dmax's and modding them go to www.dieselplace.com , thats where all of the leading authorities on duramax's hang out.

as far as what year its pretty much your call, the 01-03's (LB7) did have injector issues but they are warrentied up to 200k miles by GM, mine are still original at 108k and no problems yet. some of the LLY's (04-05) did have some overheating issues but im pretty sure thats all been fixed by now. the LBZ's (05-07) i dont know a ton about but im pretty sure they were the first years with the variable turbo which gave it more power. the newest generation is the LMM which i believe is just about the same as the LBZ but with a little more power and the new emmissions standards including the DPF in the exhaust. and as far as reliability goes they are holding up very well, theres plenty of dmax's with 300K+ out there, ive personally seen a couple and even seen one with over 500K and have read about one with over 700K on the clock. now as with anything if youre making huge power and beating on it hard then it wont last as long but thats to be expected.