Best advice... dump the stock for an after market.
My M3 is approaching a year old next weekend (21st Dec08). While it was stock for 9months i racked up 3657miles. After deciding to spend some dosh on the car in OCT/NOV to fit a Gruppe M intake and Vorsteiner Titanium exhaust, I've racked the car up to 5730miles. Its been sooo pleasurable to drive since the exhaust upgrade.
Am now waiting for the AA X-pipe for the added grunt and minor power gains due in late DEC08 or early JAN09
Go enjoy your M mate