The hardest job have been taking my Mini totally apart and restoring it from scratch. The best mod have been making a new engine with upgraded head and overbored block.
The most difficult project have been putting a 3.2 litre turbo engine in my brother's BMW 325I E30. There ain't much space there.....
The worst mod... Helped putting a 2.5 litre m20 6 cyl. engine into a BMW 2002 and then get pulled over by the police after two days

New engine....