I personally dont believe the shorter life is from the "emissions crap" as for the balance shafts.. thats not the engine thats the coustomer that dosent want a "vibration" the engine isant out of balance but the longer strokes and weight savings of the modern crankshafts. on 4 cylinders make the engine " vibrate" but not a out of balance vibrate. so lets add some balance shafts to smooth out the seat of the pants feal...those shafts also use up hp and millage...and wear stuff out...as well as adding weight to the vehicle. many of the failures are due to cost cutting crap. like thinner castings or bigger holes in castings, leaving out supports in the castings that tie one serface to another. gm had major issues with the gen5 big block heads as so many supports were removed and thinner castings..result blown head gaskets from the head getting dips in it where the supports were, as well as the seats moving around... ex sets moved a **** load as it heat cycled causing the seat to sink on one section...( intragel seats not removable just part of the casting and hardned.) once you do a valve job and serface the heads...there good to go as the iron has found it's happy place. look at all the new gm v8s discentragrating....the fix put thicker oil in... like gm does all the time its a patch.nothing has been fixed.