Boxster 986 usable wheel sizes?

[Mikluuutus]

I'm buying winter wheels for Boxster S (year 2000) and would like to know more about what wheel sizes I can use. Manual says only these sizes:

17-inch:
front 7Jx17
rear 8.5Jx17
Offset 55mm, 48mm, 50mm

18-inch:
front 7.5Jx17
rear 9Jx17
offset 50mm, 52mm

Now I'm specially interested can I put 16-inch wheels like these:
front 6x16, offset 50mm
rear 7x16, offset 40mm
without any modifications (spacers etc.)?

or can I put these kind of 17-inch wheels?:
front 6.5x17, ET55
rear 8x17, ET40
without any modifications (spacers etc.)?

Does the car's behaviour change a lot if I choose to take either those 16-inch wheels or those 17-inch wheels specified there or do they even fit to the car straight away?

Thanks in advance!