I posted this some time back. Proper alignment makes a huge difference and saves tyre wear.
Had my wheels aligned and it made a big difference on the road. Previously my front tyres wore out on the insides leaving lots of tread accross two thirds of the tyre - the car ate front tyres every 5k miles! I now get much better, even, wear.
You do need a good alignment centre though and they need to have the shims to be able to make any changes. Having my four wheels done cost £211.
It is also worth making sure the centre has the correct measurements. These are for a 4200 Coupe:
Toe-in 2.5+/- 0.5mm
Caster +4 degrees 35' +/- 6'
Camber -20' +/- 10'
I think you are UK based and local to me arent you? If so, let me have your fax number and I'll fax over the bill and alignment report for my car. It will also give you the contact details of the specialist that Dick Lovett use in Swindon.
Alignment etc on these cars is altered by changing shims so general tyre places wont be able to do it. Email me at [email protected] if you want this info. Paperwork is at my office so I wont be able to get it to you until Tue.