This adapts a 70mm internal diameter pipe to be taken from the side air vent into the engine bay on an MGTF or MGF automobile. I added a triangle mesh in order to allow air filter material to be placed between the outside of the adapter and the stainless mesh on the outside body panel. If practicable, the air pipe could bypass the standard air filter box and go straight to the throttle body. The unused standard air box and associated smaller diameter air pipes could then be removed from the car, saving weight and making a more direct route for ram air. This would also allow easy access to the filter material simply by removing the outside body panel to the vent, for cleaning or replacement purposes.

I printed the model in Eryone TPU 95A which is tough and flexible enough to make fitting a doddle yet robust and rigid enough to withstand the environment and mechanics of use.

When printing, the adapter model is placed on top of the base model at a height of 3mm, which is the thickness of the base.

I'm printing using a 0.6mm nozzle and layer height of 0.28mm.

The Base model uses the following settings:

"Wall thickness" = 1.2
"Infill Density" = 100.0
"Infill Pattern" = Lines
"Infill line directions" = [0,225,90,315,180,45,270,135] (for improved layer integration and homogeneity)

The Adapter model uses the following model specific settings:

"Wall thickness" = 3.0
"Top Layers" = 0
"Bottom Layers" = 0
"Infill Density" = 0
"Z Seam Alignment" = Front

The Mesh model is 4mm thick and placed vertically centered inside the Base model and uses the "Modify settings for overlap" option in Cura with a "Cutting Mesh" and "Select Settings" to form the mesh. Configure the Mesh model as follows:

"Wall Thickness" = 1.8
"Top Layers" = 0
"Bottom Layers" = 0
"Infill Density" = 12.0
"Infill Pattern" = Triangles (or other preference)
"Infill line multiplier" = 2

Once printed, the base of the print can be sculpted (I used an abrasive flappy wheel in a grinder) to round sharp corners and reduce the size to fit inside the standard plastic moulding (as shown in the photos).

Update:
I added a version for two air feed pipes, with a divider, corresponding to a separate model of mine:
https://www.thingiverse.com/thing:6797540