hi I have a bf which has 360rwkw.it boosts normally most of the time but every now and then it will only boost to 5-10psi then only hold that.And also there is some times a rattling noise from turbo side during this problem.

the turbo has been ported and actuator changed, all bolts are tight

any help would be grately appreciated

lol. Im sorting of having the same problem atm with my new ported turbo. Maybe they ported it too much and its bleeding boost. Or another prob may be the flapper arm is getting caught on something. On mine I found that the flapper arm had been bent slightly and it may of been rubbing on the exhaust joiner, so I grinded the joiner back a bit to give it full freedom of movement again.

its weird because when it happens and you back off and then accelerate again its fine.Had engine rebuilt and problem only started about 4000km after. Did you have to pull turbo back off to find problem?

It sounds like you have a 9- 12 psi actuator. When the actuator opens the spring pressure isn't strong enough to close. Also with the bigger flap it takes more spring pressure to shut so when you back off it closes and the boost controller keep it shut unit it get to the correct pressure.

so it could be the actuator? too soft?

Maybe. I think the standard actuator on the FG is around 8 pound or something near that. Try 12 pound actuator and see if that helps.Maybe even try 15 pound.

Running 360 rwkw I would be using a 15 psi actuator but your tuner should recommending the correct actuator for the problem.

the car was all done by the tuner and havent had a problem until recently

could be the cat moving slightly sometimes under hard acceleration then when you back off it goes back into place freeing up the exhaust, just an idea

"high flowed cat" lol