2005-2006 Mini Cooper S are the ones to look for. Cast Iron block, last of the Super-Chargers and the gear box ratio's were changed for faster acceleration.
After 2006 they went to the French motor that is known to have chain tensioner failures and sometimes the vacuum pump bolt snaps taking out the timing chain.
https://hausofminis.com/2015/05/is-it-time-to-replace-the-timing-chain-on-your-2nd-generation-mini-cooper/