Flexible ignition wires are extremely popular and much more user-friendly over ones that are stiff and hard to bend. Magnecor ignition wires are extremely flexible due to the materials they are made from and quality that is put into each spark plug wire. Some aftermarket spark plug wires are extremely tough to deal with and do not fit inside the factory spark plug holders.
Testing out the flexibility on ignition wires can say a lot about what they are made from. Magnecor wires are made entirely from aerospace silicone rubber which is very strong and flexible. Their OEM replacement spark plug cables can safely fit into the factory spark plug holders because of this. You will not have any trouble fighting the wires trying to make them fit.
The bigger wires will be a little more difficult to fit, but they are still more flexible than the competitors. Making spark plug cables from cheap materials is what gives them a stiff feel. There are also some aftermarket ignition cables that have tried to imitate Magnecor wires with similar flexibility. These companies use low resistance conductor cables that are nowhere near the strength and durability of Magnecor ignition cables.
All of their other performance ignition cables use a multi-layer insulation jacket made from silicone and rubber blend to be as flexible as possible. Struggling inside the engine bay while replacing your wires is something most of us want to avoid. They can bend easily where you want them to go and the bigger ones are able to be routed much easier.