[husker boxster]

1st thing you'll quickly learn: affordable and Porsche wheels are mutually exclusive.

For 18 x 8 front wheels, you'll need an ET (offset) of 50.
For 18 x 10 rears, you'll need ET of 47.

If the 996 wheels have similar ETs, they'll work. The fronts are generally similar between the two. The problem occurs with the rears. They may be quite a bit off (like 65 vs 47).