Depends how confident you are at removing the original cables/outers and if you have sharp enough cutters to trim the inner & outer cables without crushing or fraying them, does your bike have hydraulic or cable brakes, if it’s hydraulic just take it in as you will need to bleed the brakes once you’ve lengthened the hoses, so you will need the correct fluid, hoses, olives and a bleed kit, if it’s cable just brake & gear cables, inner and outer, some ferrules to cover the cut cable ends as I think your shifters will be in the wrong place too., if your not confident just take it to the lbs.