Cabrio rear suspension help

hi all me again i have some vmax coil overs on my cabrio and at the mo i am running some d90 porker rims, however the the suspension seems very soft and with any weight in the back or going over bumps the tyres hit the arch, looking to replace the rear coil overs with a similar set up but with the ability to change the stifness...any suggestions......can you put camber on the rear wheels as well and hom is this achieved.....

You can adjust camber but its complicated, you'd need to fit wedge shaped washers in between the rear beam and stub axles. So, the manufacturer's recommendation is that camber and toe is in factory set and not adjustable. Personally I'd not be adjusting rear camber to fit tyres within the wheelarch; I'd be adjusting it to achieve best suspension geometry bearing in mind tyre wear and grip - the factory setting does fine for this.