whistle

[vr-man]

have just put new gas converter and gas ring on my vn as the other system was old and had continual backfiring. i had to remove the original broken airbox and replaced with pod filter. since then i have replaced the plastic intake with stainless steel. however i have this whistle through the pod filter at very low revs just on take off. apart from driving me nuts i have absolutely no idea whats causing this problem as i have never encountered it before.
would anybody have an idea what the cause is or how to stop it.

[vr-man]

problem fixed .removed cold air intake pipe and put mushroom drift pod on gas ring problem gone.