I'm not sure that hose is connected to anything. That's incoming air tube, the MAFS is just to the right in the pic and the turbocharger bottom left (for those wondering where we're looking). It's not a vac hose.
You could replace the vac hoses, which might help - 3m of 3mm hose from Supercheap is what I used last time I did it. But I think before you go grabbing more tools and stuff, try getting hold of a bluetooth OBD adapter (ELM327) and an android app called "Torque" so you can monitor the ECU's reading of the boost pressure.
If boost is lacking, your power will be significantly down. Replacing the hoses is a good first step (the hose cost me about $5 per metre, and you cannot hurt anything if you replace it one piece at a time so you can't forget where each bit goes).
If you still lack boost pressure, try this (not for too long though): take the vac hose that comes across the motor and onto the BCS (it's bolted on the hard pipe leading to the intercooler, sort of just in front and below the alternator). Connect this directly to the turbocharger and take it for a drive, but do NOT back off the throttle quickly. If boost improves (and it's all new hose) then your BCS is probably too tired.
You have two choices with the BCS. Buy a new one from Nissan ($240 I think) or from eBay ($35 like
this one here). Alternatively go to
www.tillix.com.au and grab one of their Tillix valves. I have one now, I got tired of replacing the BCS, and although my turbo isn't ECU-controlled any more, once you've adjusted the Tillix valve properly you don't have any trouble with it. Mine's been good for ages now.
