Front spacer worry...

[mr wilks]

Mine rubbed on heavy compression with 15mm at the front M sport suspension 107's and 108's.

This comes up time & time again & reality is a E85 Se , E85 Si , E86 Se , E86 Si all ride & sit every so slightly different so a set up that works fine on one might just cause a rub on another

 

[Toe-side]

You are spot on Mr Wilks. I would go 10-12mm . From a visual point of view I doubt you would notice the difference

 

[soundb0y]

I think 12 at the front is a good compromise. I wanted 15s originally but was offered a good deal on some 12s, cant really imagine that you could notice the extra 3 mm and just stops the rubbing worry.

20s should always be fine on the rear.