In addition to Ground Control/ Koni kit...

I recently ordered the custom groundcontrol/ koni coilover kit. I talked to the guys at GC about what I need to complete this set up. They told me I will need new front strut mounts, which makes sense and they dont currently make their own for the EP3 chassis. Now, for the rear, they told me I would need 4 new shock absorber mount bushings (51631-S2A-004) priced at 28$ each from Honda, as well as 2 new collars for the rear. Im wondering if I really need these new bushings for the rear, or if there are any aftermarket solutions. Im also wondering if I need any more hardware for this install. This is my first set of coilovers so Im not entirely sure what other suspension components are going to be re-used and if I need to replace anything else while were down there. Thanks in advance!