2011 Convertible SS LS3 MBRP Catback bracket?

[Level954]

This question is about S7018409 MBRP Catback.

Spoke to Phastek and MBRP yesterday to make sure this catback would fit a vert and phastek said they didnt see any restrictions and MBRP said yes.

Searching other vendors and comparing pricing turned up a product name for this part number including "11 convertible must purchase MBRPAD1710"

This is something that MBRP and Phastek did not mention to me at all yet other sites say it must be purchased.

Does anyone know what this bracket is and whether its truly needed? If I had to guess it braces the underside of the exhaust and maybe the oem doesnt fit because this exhaust is bigger?

If it is needed, is there anything else that I should order with the exhaust as far as parts for an easy quick install?

I dont have experience working on cars beyond changing oil and brakes but I do work in construction and DIY exhaust system seems relatively simple. I just dont want any surprises that will cause the car to be left on jack stands waiting for a part so all help is appreciated.