As above my 855 t5 is holding back under wot one minute shes boosting 18psi then the boost dives down to 12psi and the car wont accelerate, feels like fuel starvation or a massive boost leak.

I had this a few weaks ago, and it would appear the vac line to the compressor housing from the bcs had blown off! i sucured this line back on and all seemed ok. till today, the vac line seems flimsy so im thinking could it be collapsing under Boost? causing the symptoms above?

Any ideas welcomed as i need to sort this asap as im to and from Great Ormond street next wk with my boy.