The factory airbox to turbo plumbing for the 80 series turbo engine setup drops to under 2.5” ID through the metal joiner just before the bend to the turbo. Also the rubber onto the turbo will be getting stiff with age and can split along the seam without you knowing it - just pulling it over the lip and cause it to split and allow sand, dust and water to entry the turbo after the filter.

Since the outlet of the airbox (pointing down) is 80mm we can supply piping to maintain 76mm if going onto a 76mm/3” turbo entry. If you are still running the original compressor cover (with or without high flow internals) the 3” silicon can be compressed down to seal around the 2 ⅞” entry - to do this just lube between clamp and silicon.

If you have a 3.5” (90mm) turbo entry, PDI have a custom one piece silicon with steel bands to step up from 80mm to 90mm all the way to the front of the turbo.