Differentials

Does adding a Mace LSD on a VS 2 vehicle with 1.9 ratio rockers and intake manifolds improve handling and performance?
Adding an LSD centre to your diff would improve handling (along with burnout performance), by distributing torque between wheels proportionally where required. We have a mechanical LSD diff centre available, as shown in the link below:
Mace Torque-Lock LSD Diff
I have fitted a new diff with a higher gear ratio, are you able to caliberate my speedo?
No, unfortunately, you would need a Tech 2 tool or a Speedo corrector box for this.