Crosstalk minimisation is one of the most important aspects of high-performance VLSI circuit design. Crosstalk minimisation in the reserved two-layer Manhattan routing model is NP-complete, even without vertical constraints. It is hard to approximate the crosstalk minimisation problem. The problem of minimising bottleneck crosstalk is also NP-complete. We have further shown that all these results hold even if doglegging is allowed. We have incorporated the reviewer suggestions to the best of our abilities.