I had mine welded on the car while the car was on a frame lift. Now before you all scream bloody murder I did not have choice. It was my friends shop and I got the work done for free. I can't tell you if how I got them weld on made a difference because I have not driven a another car with sub-frame connectors. That being said the one thing I would recommend is to paint them before you get them weld on. The sub frame connecters are bare steel and will rust.
There is an added bonus! Now I jack my car on the subframe connector mounts which mean that I don't have to remove the side skirt jack point covers anymore.
