I've been running around 1-1.1bar on my stock 33GTR turbos for 18months or so, it came like that from the previous owner, so who knows how long before that he was running it.
By just removing the restricter you won't get 1 bar, a little under, and if you dont have a full exaust then a little less once again. I'd remove it if i were you. But everything lwells said is right - the turbos could be tired and they could let go, this will just speed up the process of them letting go... If you don't remove the restricter they may last 12 months, if you do remove it they may only last 6months etc... its up to you. The biggest thing to worry about is if they do let go, the exaust wheels getting sucked back into the engine and damaging pistons.... so if you hear a bang, keep your foot to the floor so the exaust wheel gets blown out the exaust