Yeah, I won't be notching the sub-frame. Ordering up the Calvert setup now and will weld it on. The subframe is already somewhat plated with the inboard kit installed..... lol
The only think about welding them on is that if the track wears you'll have to grind the welds and repeat to replace it. If you made a plate with threaded inserts you could drop the whole slider if you needed to replace parts later. Probably not necessary for a lot of cars given the lack of mileage.
I wanted to be able to R&R mine if I needed to in the future. Given the bearing arrangement the wear on the slides should be minimal so it's probably overkill.
There still is some, but it's a lot less than the flex you'll get from the bushings on both ends of the shackle, especially since the shackle acts as a lever arm on the bushings when you side load the springs.
