[wagonwheels]

I've been chasing a performance issue for 6 months or so with my 2010 xc70 d5 205.It has a definite flat spot from 2600rpm to 3000rpm.There are no codes on vida and boost looks ok from what I can see.I did replace my bottom intercooler hose as it had a tiny pin hole in it and smoke tested the intake side of things with no obvious leaks detected.I did the smoke test as I feel it hisses too much under full throttle at lower rpms .
It's also fairly poor on fuel (28-30mpg) and compared to my 2004 xc70 d5 163(shark remap,egr delete, stainless exhaust and intercooler) it feel weak especially low on torque.
I wonder if being the twin turbo set up that one of the plastic joining feed pipes might have split on the turbos but I cant find any info on it being an issue.
Any info greatly recieved.

Stuart