I think the word modified is inaccurate. It had had its geometry adjusted with more aggressive cambers. To the best of my knowledge this had been conducted by professionals. He had even raised the car in order t reduce the rubbing issue and from what I understand is not the only one to have experienced the rubbing at The Ring or other tracks in Europe.

AP gave a heads up to the compromises accepted by the design team when going to a 21" rear tyre. They obviously had their work cut out for them in terms of lifting the bar significantly on their previous offering (GT3). The rear springs n the RS for example are now progressive rather than linear as they are on the GT3 and the keeper springs are incorporated int the strut design rather than sitting free on top.

IMO the front rubbing is more an issue of castor than camber. Altering castor by adjusting camber (beyond -2.0) without using shims and a modified LCA inset will alter castor and create increased rubbing n the front liner near the indicator. This is true on the GT3 and exaggerated on the RS due to the shape of the liner (as the indicator is "fatter"). 

I think the rear 21" is a bit of a compromise in the RS. The benefits of the additional width I am not sure counter the real world practicality of finding a wide breadth of tyre options for those using the car at the track and of curse the 21" tyres are more expensive. In a decade time there will be 21" R cmps available by a number of manufacturers but by then most RS will probably be in private collections! After two years we are nly just hearing that Hoosier will be making 20" R7 for advanced track work in 2016 (if the rumour comes true). At this time there are two options in GT3 sizes available for the track. 

I understand why the factory wanted 21" because it increases the contact patch around 5% over using a 325 on a 20" rim. Im Just not sure that the overall compromises in tyre availability and cost for the track rats is worth the 1 or 2 tenths this change realises at the track and the potential for limiting the geometry (without causing liner destruction), tyre choice and cost.

These are my views on the subject. Kept on factory geo and used on the road as PeterM will be I see no issues for concern however...


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2014 991 GT3, 1994 993C2 6spd RS spec, 2016 Cayman GT4 (on order)