E46 BMW 320D - Cheaps mods to improve the handling - iworld

I am thinking about improving the handling of the car - it sits on soft suspensions and on 18" M tech wheels - but i got a lot of inspiration from the top gear episode featuring the 24hr race with the 330D

Is it a good idea to put a front anti-role bar on the engine bay area?

Is it a good idea to get a front splitter with tray underneath the car?What would you recommend and do you have any good links

Any other mods?