Growling - rumbling sound

[Si_is200]

Had the window fully down and noticed when pulling up from low revs 1000-2500rmp there's a growling rumble similar to a blowing exhaust sound but exhaust is fine no leaks... It's strange doesn't judder or effect anything else just wondering if anyone had noticed this before or has any experience on this mystery sound 

[steve2006]

Maybe a wheel bearing?

[Si_is200]

inspected that when installing the coilers, but could be possible although i would expect noise/pitch would change as speed changes, but it comes in at particular revs then disappears, just thinking this sound has only come since i remove air intake resonater pipe and sealed up the hole.... so if anyone was interested in doing that mod can assure you won't feel any improvement at all but may gain this very very tiny increase in noise