2 years ago i seen a HD break 2 rods with just a pulley change. i rebuilt the motor using H beam mahle rods stock crank, however the guy ordered a 5.8l big bore block from MMR so of course it would need a bigger piston.
i don't trust the stock rods above 450hp. but the HD never made 400hp. do your self a favor just buy a set good rods and pistons, you do that and you take care of the engine you can hit 150K miles.
We're running my bro in laws HD with a 10lb lower, factory HD upper, fore fuel hat, 80lb inj, 2 255 walbros, kenne bell bap, and a mafia. His motor is 53k original and the eaton is factory unported. He even has the factory manifolds on it. Boost hits just over 15psi. It dynoed 466/566. It runs on E85 and is tuned by 04sleeper. He's been running it since April and it's a 4 dr beast on the streets, the eaton just screeeeaaaaammssss. No signs of letting go on that ethanol, solid fuel system and tune :rockon:
Mine held together for prob 50k+ miles in the 420-450 range @13-15# w 2.3l kb, got tuned w 8# lower solid 15-16# dynoed 478hp 570 tq broke rod 3rd pass down the track.
The ratings of the stock rods seem to be up to about 450, beyond this they are unreliable, below this they can be unreliable if detonation exists. The best thing to do if you are approaching these #'s is send the block in to us for a Forged rebuild ($2399)or look at one of the MMR Forged shortblocks (starting at $3199)