Hi folks, I've read mixed reviews on the benefit of fitting Watts linkages to Caterhams. 
My 3 yr old (12000 mile) 620S SV has always been 'nervous' on fast B roads especially when 'not on it hard'. 
I fitted the Watts link from Caterham and am astounded how much the car has calmed down. It's almost relaxing to drive now, the death grip on the steering wheel has now gone.

I did however re manufacture the 'bell crank stainless steel bushes' supplied with the kit, they were way too loose on the bolt also didn't support the axle webs well enough - that may account for some negative comments on becoming noisy.