The interesting question would be : what is the acceptable distortion level for "safe" engine performance and how much of this is affected by upstream disturbances - helments/roll hoops/upwash/turbulence from other cars
You describe roll hoops (the high thing that stops drivers head from being squashed when car rolls) or airbox apertures (the hole that allows air to enter engine)? The roll hoop structure nowdays is often obscured in bodywork and it is difficult to assess its shape.