It sure doesn't look like much ground clearance you've got there.
Are you sure reverting to stock springs (perhaps US-spec M030, if you want a sportier ride) wouldn't be your best bet? Biggest cost is going to be labor to remove and tear into those struts again.
In case you are interested in adding thicker spring perches, below are a couple of the thicker stock spring perch options for you, (at least, for the rear of the 986 boxster).
These will definitely fit the rear, although I can't remember whether the fronts call for unique parts vs the rears (however, consulting the Porsche parts catalog would quickly and easily clear that question up).
A funny thing is that Porsche originally had a thinner (3mm spec) and a thicker (6mm spec) rubber spring perch options for our 986's, but then the thinner rubber one got "superceded" to a seemingly very thick polyurethane 987 part!
6mm spec, 986 rubber rear perch:
Porsche's superceded part (987 polyurethane style) for the 986 3mm spec rear rubber perch measures to a whopping > 14mm uncompressed thickness! (What was Porsche thinking?)
Not sure if you might be able to stack these up, if one weren't thick enough.
I will add that 987 polyurethane piece also seems to be softer, so may compress much more than the harder rubber version under the considerable weight each needs to bear. Haven't actually installed them yet to see.
I'm actually looking for the 3mm old school rear 986 rubber mounts - (anyone have a set of new ones they want to sell to me or trade/swap for either set of mine, let me know!)