I only know the Garret's myself, the gt2554r is a great option to about 250hp or less than about 14-15psi, after that effiency drops quick with the size of the exhaust side, the gt2560 is a slight step up offering a slight gain giving you up to about 16-17psi capability or about 275hp. many run higher than that but effiecency drops so quick at those levels hp per pound of boost gains are almost non-exsistent, going to or above 15psi means you have to start looking at new ignition options to start retarding timing, at about 16psi or above now rods are in order and clutches need to be looked at as the stockers durability starts to come into question.
With that in mind, 10psi is not equal across different turbos/setups, larger exhaust sides will flow better and make more hp at any give psi, but at a cost to lag, a gt2860rs will make a lot more hp at 10psi than a gt2554r will but there is a noticable amount of lag difference between the two, my sled makes boost at an idle with the 2554 but with the 2860 there is just a slight amount of lag noticeable, enough so that I find it uncomfortable for boondocking but one does get used to it and learn to drive around it to some extent.
these ballbearing turbos are great but do put out a lot of heat, probably because they are always spooled up and working, but I would recommend you install some additional cooling for them, I run an aftercooler for the oil, just a modified tunnel cooler I cut down and installed threaded inserts into so I could pump the oil through it before it gets back to the engine, and I run a precooler for the coolant, same design under tunnel cooler modified so the coolant gets very cold just before going into the turbo, dropped my engine oil temp by about 40deg, and intake temps by almost 80deg! performance is a lot more consistent now too since the temps are more stable even after making multiple climbs back to back it just doesnt have the heat soak like it used to,
