^ PB Laster works even better. The factory always overtightens plugs. On all cars. It's going to take some umpf to break them lose. As long as you have the proper socket/tool on it and you are square, put some torque on it. Make sure to use anti-sieze on the threads of the new ones. I also use di-electric grease on the plug boots.
'07 335i Sedan, base pkg, 6spd Manual, Procede 3 V5 w/NLS, Macht Schnell Downpipes, 18" Staggered 313's w/Conti DWS's, OS Giken TCD LSD, VAC Street Diff Cover, Dinan Oil Cooler, Dinan Intercooler, Akebono Euro Pads, CDV Removed, Black BMW Grilles, Interior & Exterior white LED lighting, LUX Angel Eyes, Debadged, Blend V1 mount, Llumar ATR Tint.