Somewhere . . . on the internet, i ran across a mention (in something official) of studies to increase the range of the Tempest by increasing internal fuel. Both the UK and US participated in the study, similar to what happened with the Spitfire.
I do not remember what the website was, but I copied down some of the data:
Tempest Mk II internal fuel was increased from 160 Impgal to 185 Impgal, and range increased from 790 miles to 900 miles
Tempest Mk V internal fuel was increased from 162 Impgal to 192 Impgal, and range increased from 740 miles to 890 miles