i have a bit of a dilema going on so here goes

i have a gt 30 roller bearing turbo with external wg and i also have a t34 currently running a .48 exhaust housing i am looking for a genuine 400 atw hp so question is am i better running the gt30 as it will make the power at lower boost levels and will be less stressed ??/
would a t34 make this power realistically ??
am i better off sellingthe pair and getting a t38??

advise and options please

regards Ian

ps this is 2wd sapph