the connection to the inlet from the intercooler is 52mm but the plenum is about 2-3 mm bigger but you can squeeze 52mm silicone hose onto it. I had a metal adapter connected to the plenum and other piping with two small bits of hose, the silicone hosing looks 10 times better, if you go to someone who deals with samco or SFS they can make you up bespoke hosing no pronlem, its fairly expensive but the end result is more professional looking, if anyone wants the ssqv to silicone hose ID adaptors let me know as I could put in an order with the american suppler, also while I'm at it I could order some 10PSI springs which are better for cars running the remaps