Help need again :(

i fitted a induction kit last week..i have started to notice that when i try pulling away from lights or turning the car round(at normal revs)i can hear a sound what sounds like air leaking(abit like someone taking there last breath or sucking air in.it seems to happen till the engine gets to about 2500 revs.then stops after the dump valve works, when i change from first to second it sometimes does it again.do you think the dump valve might be leaking or can the waste gate stay open...i seem to loose power as well for a second or two(like really bad turbo lag)...does anyone no what it is,there is no management light coming on,has anyone heard of this before. :eek:

p.s i got my money back for the manifold of ebay..full refund..nice

Edited 12 September, 200817 yr by HaRRyBoNgO(uK)