is it worth installing cam in stock 318?

Well, it started in 2010, but post #21 is a new inquiry on this theme.

For element303: If you want a lumpy idle, be aware that you will dump some fuel mileage. Going with the Hughes Whiplash will give the idle, but the 107 lobe separation angle that creates the lumpy sounds is what will also lower fuel mileage.

If you can accept that, then I personally would go with the Whiplash (though I never go for a 'sound' as a goal; a well built engine will have a good sound as a byproduct). At least you get some good lift to help cylinder filling at lower RPM's; that will make better torque. You surely need better valve springs and ones that will accept the higher lift without binding. Make sure you properly time your new cam!

And lot of the sound in the video that you linked comes from a much more open exhaust. You're not going to get that exact sound without a lot more than a simple cam change.