They shouldn't rattle but they are quite a noisey engine compared with say a 328i,lots of evo's have noisey vanos & they run perfectly well for years like that, its only when the power drops off you need to worry. Their are people out there now that will recondition the vanos units for less than half the price of a new unit from BMW. I have a bill from the previous owner of my M3 Evo for just over £2000 to renew the vanos at 70k miles .

Shells can spin & damage crank if you over rev engine the conrod bolts have a habit of stretching, lots people use ARP bolts.

Simon.