Problem after motobox install?

Installed motobox, motos secondary flys, removed sas.
When revving in neutral, i had a few of very loud pops coming from near airbox/throttle bodys.
Only happenned when whacking open the throttle quickly.

Maybe sucking in air through the rubber couplings joining throttle bodies to manifold??

Any suggestions on what mite be the cause i would appreciate.

ps. have fmf apex exhaust and ktm akrapovic fuel map.

Sounds like a possible air leak to me. Check to be sure the TBs are seated all the way in the boots that couple them to the manifolds. Also be sure that the hose clamps are snugged down tight.

Worst case is that one of the boots cracked/tore and is leaking...