Hi,
Foam surround do not need run in. The surround will have to be of the same geometry, the density & shore hardness will also needs to be the same as in the original. And in many cases the foam materials... poly foam, poylether foam, Hd foam LD foam... ect. I can supply you with the closest one, which will ensure the sound to be exactly as same as before with guarantee
If you want foam surrounds for your Infinity SM 65. I can get you the original replacement surrounds for your drivers. I am about to get parts from abroad which will be finalized in a day or two.
Kindly confirm ASAP so I can add them to my order list.
Vivek