Originally Posted by bob s2zvh
my mates s2 had a similar boost problem! turned out 2 be a sticky actuator!
i thought about this ill have to look at it wen it stops raining.
as for the jolting its the sort that u get wen you get fuel starvation and it doesnt affect the boost. When it only hits 4-5psi its usually after hard acceleration although it does just do it sometimes