Factory stock boost on a 34 GTR is .9 bar ( a little more than 33 gtr). Stock 34 gtr turbos on standard and V-specs are ball bearing and ceramic exhaust wheels .
Its up to you on how much boost you run on stock turbos ( if you have stock turbos) but I wouldn't go over 1 bar on them. The problem is if one lets go it could destroy your engine because when it lets go it breaks into a million tiny pieces ( like sand dust) that can be sucked back in to the engine .
If you want to get more power for your stock internal engine just buy a pair of HKS GTSS turbos and a power f/c tune that to 1.1 bar and enjoy it, if you want to track it you will need a better cooling system, radiator and oil cooler and better brakes . The problem then you will run in to is the small amount on oil the RB26 sump holds so you will need sump baffles and maybe a bigger sump ... Where do you stop???? When you get sick of spending money on her?? maybe ???