OK heres your answer as i have been on the phone with DVLA this morning about my focus cossie conversion, they checked and double checked and came up with the following

- if RFL (road tax) is based on emissions or not

The original emissions/ tax bracket is based on the car NOT the engine, so i can put a 2.0ltr in a 1.4focus and still pay road tax as if it was a 1.4, all you need to do is put in writing the engine size and engine number and send it to them with V5 and thats it, obviously it would have to be insured under the new cc but im ok cos im on a trading policy as easy as that



if your not changing CC sizes then is does not matter as long as your insurance covers you with a turbo conversion