I want to change the bars on my Focus to carbon, I contacted Focus who said they cant advise to change anything as all parts are designed to be safety compliant etc - is this just them covering their backs or is it not a good idea?
Mate, this whole game is about everyone upgrading everything all the time. Just put your new bars on & be happy. If your bike subsequently explodes, & you need to warranty it but are worried they'll deny you, then stick the originals back on & let Focus sort it out.
I would not expect a brand to recommend anything they did not fit a standard but as per the post above that does not mean it is unsafe or unwise. Provided it is not a part that could negate any warranty claim on the bike (e.g forks with greater travel than might be specified in the bike manual) , just buy a branded product with a good reputation, and if you want carbon, expect to pay a fairly big premium for a well made product.
Don’t own a bike that I haven’t changed the bars on. I’m actually surprised that Focus would give that answer on a component like bars. Fork and shock, I get but that advice on bars is daft.