On my Ferrari 360 replica I used poppers and they were nothing but a nightmare! And if your battery goes flat its game over! (I recommend putting a charge point somewhere under the car or behind a bumper!) I'm not 100% on this but I was told when I fitted mine that they may fail an MOT as there was no mechanical way to get into the car? Mine didn't fail the MOT but then again it didn't fail on the emissions even though it didn't have a cat or back box
I would recommend using the remote locking system from a ford transit van though as they are more robust - My mate fitted these onto his focus.