just looked through a VW brochure for the specifications
the unladen weight of the 140 GT is 1281kg, the 170GT is 1293
they both have a gross vehicle weight (unladen weight+ occupants and luggage) of 1870kg
so i'd expect the cars to have the same suspension set up and the the same results when fitting the sportline springs
the small difference in the unladen weights would make the ride heights identical in both cars and could be made up from eating more doughnuts and burgers
the other question about using standard dampers with new lowered springs
don't do it with a car that has done over 55-60k, it's a false economy
on the other hand on a MK5 with relatively low miles I decided to take a chance on the standard Sachs dampers and can honestly report an allmost standard ride comfort
might be different if the car was being lowered over 40mm