I don't know about that I thought it was more a case of getting it flashed.
This was DW's summation with the flash and exhaust, which seems fair comment to me

Dave being a true Yorkshireman I knew it needed doing

..Tailpipe: Was black and sooty. Now is a much lighter grey.
So obviously I'm delighted by this transformation. The improved fuel economy must be related to being in a higher gear, and only needing the lightest touch of the accelerator to maintain progress.
The whole feeling is transformed from a breathless poor revving engine into something which revs freely and pulls hard. It's not a cheap modification, and is how the Plus 4 should have been from the start. I would have been over the moon if this Morgan had felt like this from Day 1. It's astonishing.[i][/i]