Merlin Motorsports – good company who sell ITG filters which are the nearest fit for me.
K&N – the standard filters everyone uses
PiperCross – alternative to K&N
Moss Europe – places that sell rams and what have-ya
RoverSD1 tuning page – they have a small section on Ram tuning
Tuning BL’s A Series engine – a book by David Vizard which talks at length about the Ram tuning and air-flow.
Pistonheads.com – the forums (Gassing Station) contain many knowledgeable people who helped me out in designing the chambers.
MOC forum discusion
MG owners – search the archives for an abundance of hints and ideas relating to the MGB but easily transferable.