Ok, I researched a lot about the truck, cause I wanted 500+hp truck and wanted to run mid 12's in the quarter, this would fit me fine and give me all the performance I need to even expect with the truck without spending over $10,000. I have always upgraded the componentry first before doing my mods. I have had several over 450hp applications in the past when 450hp was considered a lot. Not so much in the last 10 years. I have blown a lot of money replacing drivetrain and motors.
Stock block has seen 650hp without reinforcing the block, this is not as high as I have seen, but as high as I have seen with 80,000 miles of use on it. I have seen a couple 750hp to 850hp hemi's out there, but many have gone through trannies, and diffs, driveshafts, motor mounts and cracked blocks. Although remember that any of this is still a gamble so keeping a safety level in mind is always smart, along with an extra $5000 of cash set aside, JUST IN CASE, unless this isn't your primary vehicle. They do make some all steal racing blocks now for the newer generation hemi's that are made for 850+hp. With stock pistons, guys are running 600hp with nitrous setups, but I have been seeing a trend of supercharger guys blowing out pistons, with only 150hp increases, but they have alwasy said with this motor supercharging is not recommended entirely due to the low weight racing style pistons. This is directly from Chrysler about the pistons! If you are planning on supercharging, either make sure you get one with a motor warrenty, like Edelbrocks, or Magnuson offers or change out your piston. If you have a 2wd motor, I heard that a couple of shops can change out the pistons from underneath after removing the oil pan, just like in a lot of the LS platform motors. Haven't verified this! Yes you can change out the cam without removing the motor,
Tranny, with torque converter upgrade and valve body stage 2 upgrade, guys have been running consistant 500hp+ levels with years of trouble free driving. I have heard you will burn out the clutches in the tranny if you start running over the 500hp mark and either dont tune for maximized tranny pressure and quick shift speed, or do the valvebody upgrade which will give you the same results as the tunning! If you are up to or above 600hp levels, they offer stage 2 and 3 trannies with stronger planatary gear setups and blue plate special clutch plates, plus you will want an all billet converter, and a heavier solid Flex plate, ours are actually spaced for lighter weight. But for the most part I have seen 600hp applications running the stock tranny fine, mostly the clutches that are designed to take up the slack are what go, so not many blown trannies, just burnt out clutches, a lot cheaper to rebuild this way. This has been a great tranny for Chrysler, especially when they don't break down very much, and they are used in soo many vehicles. Since 2006 and 2009 the trannies each time also recieved internal upgrades that have made them stronger, so 2009 and up versions are the strongest ones in the pack.
Driveshafts, unless you are running very high speeds, then go with a light weight balanced aluminum, otherwise no probelms I have able to find in research.
Differentials, we know in 2011 and newer models, that they went from the 9.25Chrysler diff to the ZF manufactured diff. I have seen side by side pictures of the two, and the ZF has a little bit bigger webbing and a slightly thicker housing. According to Ram, the same diff is used on the basic 2500 truck with Hemi, and many heavy towing guys over the years have complained about leaking and chewing up of teeth on the Chrysler diff, leading Ram to us the ZF diff which is rated at 22% stiffer housing for less flex, less chance of gears eating up eachother with also leads to less chance of seals leaking. So stronger and same price point. I have not heard squat beyond this about the rear diff problems from anyone, but you can get larger splined axles, and they do make billet end caps, with ARP studs, also they have steel reinforced back plate that stiffens the whole housing and has main cap stabilizing bolts, just like those diff cover plates they used on high hp Mustang and Camaro rear ends but this is on the Chrysler diff. So most guys I have seen running fast ass trucks are just using the stock rear end. And I have seen one guy running mods plus a lot nitrous blow up his driveshaft at 120mph when the truck shifted, this was later found out to be, not balanced to high rpms which caused it to blow when shifting into 4th gear at 120. No problems with new driveshaft.
Cooling system, stock setup on 700hp applications no problem. Fuel upgrades over 550+hp applications recommended larger fuel pump, or injectors depending on setup, Coils are good to 850hp applications, I have only seen some guys use a MSD control box that help boost the stock coils. Fuel lines, stock lines using larger fuel pump and injectors or fuel booster good up to 850hp.
Now most of the components that hold the rear end are much much stiffer than the bent sheetmetal that they like to use in the mustangs and camaros of old. Our links are tubular, with solid mounted pivot points, plus the panhand rod, are pretty damn stout. If you have taken apart this supension doing a lift or lowering you will see what I mean, no need to upgrade any of these parts beyond stock. It will handle most anything you will throw at it. Of course once agian, if you are running a 700+hp setup, than everybit helps, so, spohn makes heavy tubed adjustable control arms for this rear end, and I would recommend a custom shop weld some support plates on the frame link spots. This would reduce the amount of flex nicely on the rear end. The mounting points on the rear diff itself are pretty freakin stout, so no recommendations for anything there.
So in other words, if you are doing just all basic bolt ons, intake, headers, exhaust, t/b, tuning then the stock setup is completely fine and will handle this no problem. Hell I have driven a stroked and supercharged fully stocked bumble bee truck with 700hp, and that was a little bit of a handfull, and was built to handle the power, but he did not have the benifit of our 4 link, for better tractions, stability, ride, and handling, like ours.
So NO worries ladie!!! Now what is messed up, go buy anyone elses truck or cars and start to mod them, and THEN see how much you gotta spend.