Lowering springs

[Alfa68]

I have a 2012 Guilietta QV.
I bought a set of Eibach sports lowering springs, from TMC in Ireland. (cheaper, even including postage than buying here in AUS)
Anyway, they are having trouble getting the springs delivered to them, to then post to me. I bought them,(as well as a larger QV specific AIRTEC turbo intercooler), in December, and they're saying five more weeks at least.
They are recommending a NOVITEC equivalent, which my own research shows to be a good option, and they have them in stock.
The Eibach springs say they lower the car by about 30-40mm. It also says that the QV is already 20mm lower than the 1.4 Multiair, so that it'll lower a QV by only 10-15mm.
I think 10-15 is fine, and don't want 30-40mm.
The NOVITEC product description also says it'll lower the car by 30-40mm, but makes no specific mention of the QV.
SO, I'm wondering if ;
A. It's fair (as seems logical) to assume it'd be the same, lowering the QV by only 10-15mm(?)
and
B. Has anyone had either product or have any general feedback for me as a novice (but enthusiastic) QV modifyer in regard to lowering springs?
Cheers,
Shane.