Curryman:ASK POPPADOM KING!!!!
Ah, the source of the PM....
Right MK3 Astra.
A 60mm drop on 17" rims is fine as long as your using 205/40 R17 tyres.
You wont be able to do it just by swapping the springs tho.
You'll have to swap the shocks, they don't like anything more than a -40mm drop.
If you don't they'll last about a month before you need swap them anyway.
Ideally spend that bit more and get a set of coilovers.
LMF would be the first place i'd ring CLICK HERE
Busy Peeling Potatos