Haynes are well known in Britain for producing manuals for car owners. I've owned copies for every car I've ever owned (except the last one - I became too lazy to fiddle with the engine). Now they are intending to bring out one to enable you to tune your very own Spitfire!!!
http://www.haynes.co.uk/webapp/wcs/s...4001&langId=-1 
I'll probably buy the manual - it's just the Spit that could be tricky to get my hands on.