After installing an aftermarket Blow off Valve and Intake the fiesta is capable of making some significant turbo noises. Depending on the blow off valve chosen and how it is set up the car can create the classic “pigeon” noise or even the fluttering noise. The pigeon noise is much louder but the fluttering noise is significantly more unique.
The fluttering sound can actually be a negative thing. Typically it is indicative of a surge of air coming back into the the turbo and isn’t necessarily healthy for the car. Luckily for us it is not a massive worry for our cars as the turbo is small, but it still could lead to a blown up turbo in the future.