the thing is this... anything below 35 (?) is illegal so it really comes down to your choice. If you go 20 you might as well go 5... if you get stopped and stickered they will sticker you for a 20 or a 5 as they are both illegal.
I use a trusted tinter (Peter Garden) to do all my work and he is excellent and reasonably priced.
The question is how big are your kahoona's???
http://www.perth-wrx.com/vb/showthre...2&page=3&pp=10
already been done too....