t5 boost only boosting in high rev range

hi guys unsure why the engine starts boost and is runing fine but noticed its only pulling from approx 5000 upwards any ideas ,ive checked codes and looked for possible airleaks none found,and ive found i fitted a upratted pump and if i accelert hard then let the thottle off it back fires doing loud bangs ,which makes my hair move,yes its decatted,rica,dv new plugs leads dizzy etc ,checked all timing too ,

changed the bcs 2day jod and double checked these vacum pipes and still dose same ,im awaiting on the thottle senor to arrive thow

zoom zoom we have lift off fitted white injectors 2day and the engine has transformed boost and pulls very nice what a buzz ,must have been knackerd or worn injectors

Hi, So a case of fuel starvation then? Des. . . ;)

yep i tryed to clean the injectors but didnt seem to work ,so thought it must be something else until i fitted some white ones seems fine ,for the time been any lol next job rip the gearbox off and fit a new clutch 30mins job in a bug ,saying something for the std volvo gearbox id say :speechless-smiley-6