Centre box replacement aberdeen

Looking to have my centre box replaced with a straight through pipe. Have seen that some people on here have got this done quite cheap. Have been around a few garages in aberdeen and the best price i have been given is £110 + vat, think this is crazy.

Does anybody know the size of pipe i need length etc.? Will just get one made and stick it on myself. Bit more work but can see this being the cheaper way

Thanks