It's good for the MMC to advise not to fit a free flow filter as the mid-range high-load fuel map area is likely to be already very weak and this would only enhance the issue, so it is simple to assume being able to either control fueling through either injection system chipping or more precise pressure delivery control are indeed paramount to any such upgrade then at least the combined upgrades will produce all that should be expected from each other.

Considering exhaust systems though the standard non-free flow (cat) ones inhibit the engine's ability to breath to such an extent that proportionally, masses of mid-range engine torque is lost. This issue is
apparent across the board fuel-injected 4s, 6s, and 8s.

Getting much more from modern Morgans is not difficult when you begin to understand the underlying issues.