Hi fran9r & welcome to the forum.
[url=https://www.bevwo.com/][color=#000000]Below[/color][/url] is an extract from the MOT Manual, which may be useful…
If a vehicle first used on or after 1 September 2002 is fitted with a different engine, you must test it to the emissions standards for the age of the vehicle.
If an engine has been modified in any way, it still must meet the exhaust emission requirements according to the age of the vehicle.
