honestly... there is nothing worth doing to the m42 engine.
suspension, sure..but to make it fast? a chip is your best bet, but that isnt doing a whole lot..... intake just adds air to your engine..but that doesnt give you gains.... exhaust..that wont make a difference....
if you really wanted a project i would say, m52 engine, new tranny, new suspension...
i am getting rid of my 318 hopfully soon.. i love it, but it just dont have the get up that i really want... i am looking at an e30 325i..then doing suspension...sick car