Fiesta ST, Sound from the engine bay after installing CAI and Intercooler

[Knower-of-nothing]

Guys i dont know if this was already occurring before i installed the CAI and intercooler but ive never ever noticed it untill now. Long story short i was parking my car when i noticed this click coming from the engine and it happens as the revs go down, after i noticed it i gave it a few more revs to see if it repeated and sure enough it did i noticed that sometimes the rev needle would just drop down after this "click" initially i thought it was a knock but its actually a click almost as though the ecu is cutting off something....the only mods i have right now on the car is the mountune CAI and a garret-cored intercooler no tune just yet, another thing i might note is that the clamps on the hoses are super tight and we checked for leaks after installation and there were no signs, please shed some light on the matter, thanks