I recently fitted the CR Tech £78 one to my 2.0 diesel
Has a little more power in the overtaking portion of the rev range, but not a huge change.
Doesn't seem to be any different in fuel, unless you trust the now none reliable computer.
Just done 2 weeks driving, same route, same miles 600 each week, 1 with box fitted, 1 without, and to be honest, If I hadn't known, I couldn't tell you which week was which easily
I'm a 'sprited' driver, point and squirt on A roads, and hanging around 80 mph on motorways.
I'll be towing my caravan soon, and hope the little extra power I've noticed, makes itself more obvious with the extra load.
If not, I should be abe to flog it on and not lose too much in the process.

Has a little more power in the overtaking portion of the rev range, but not a huge change.
Doesn't seem to be any different in fuel, unless you trust the now none reliable computer.
Just done 2 weeks driving, same route, same miles 600 each week, 1 with box fitted, 1 without, and to be honest, If I hadn't known, I couldn't tell you which week was which easily
I'm a 'sprited' driver, point and squirt on A roads, and hanging around 80 mph on motorways.
I'll be towing my caravan soon, and hope the little extra power I've noticed, makes itself more obvious with the extra load.
If not, I should be abe to flog it on and not lose too much in the process.