In offshore what is best installation method for 4" retrofit riser in more than 70 meter water depth, is it very flexible?

The level of challange for the Riser installation in the water depth above 70 m will be driven by the selection Vessel, crane and davit embedded onboard. Its depend to the tools provide. if the crane with limit boom length or capacity then the riser may be separate in to two section with flange connection and AWTI (underwater tie-in) by the divers. but if the crane provide with sufficient capacities then stalk on may be one of alternative method to be applied. However The lifting analysis shall be performed to defined the cog (lifting arrangement) and flexibility of the riser due to small diameter size.