I upgraded to the VAC oil pump sprocket, oil pan baffle, S54 timing chain tensioner, ATI damper, carillo rods and some better bearings. I've had the stewart water pump for awhile with great results...many OEM M3s (E46 and E9X) were going into limp mode last summer and I was still abusing my car...with no oil cooler.
I will be upgrading to a Zionsville radiator/expansion tank as well.
2013 F30 328i - Melbourne Red
2011 E90 M3 - Monte Carlo Blue
2004 E46 M3 - Imola red