Castor plates - how much to increase
 

I'll be swapping out the bushes in my 2005 STi lower control arms soon and have obtained a couple of strips of 12mm ally that I've made into castor inserts/plates to fit between the control arm and rear bushing pin.

Is 12mm too much? The free castor mod would gain 5mm (?) distance roughly by swapping the pin around and I've heard of people adding is castor plates along with this also but never 12mm.

If I don't perform the pin flip but do use my castor plates then that's an extra 7mm on top of the castor mod which seems reasonable. If I do also perform the pin flip and the plates then that's 17mm which seems excessive.

I dont want the expense of castor top mounts, the potential free mod of my castor plates was the dangling carrot.

Thoughts or input welcomed