No self respecting show car owner would dream of leaving the doors on their car standard. The Lambo door conversion kits are becomming popular as seen in this Peugeot and Nissan. You get what you pay for and the cheap kits will often fail or not open smoothly or properly.
The weight of the door needs to be correctly sprung and to do this accurately you should buy a kit specific to your car – there is a massive difference between the weight of doors from different manufacturers. The mechanism sits in the wing and usually requires welding into place and a respray over the cut area. This puts a lambo door conversion out of the reach of the DIY car styling modder.