In Reply to: considering buying a 89-93 535i posted by BMWenthus on January 25, 2000 at 17:47:05:
: One other item that makes a significant difference is extrude-honing the intake manifold. Significantly (seat of the pants) added torque to the lower rpm range.
Can you explain the process a little? Is the aim to increase the bore of the manifold, smooth out burrs, match the ports or what? How does it help low RPM torque?