GT3 muffler on 3.6 transplant, questions

[edm981S]

Hello experienced GT3 muffler fitters to 3.6 swaps. Any of those unicorns on the forum to help answer some questions?
I have Moses' 1983 Targa with the 3.6 Varioram. I want to get a better sound out of the car as opposed to the cats, straight pipe currently there. My current configuration has BB headers with heat. I also have the Iroc rear bumper.

I have a 991.2 GT3 center exhaust and also have the side cans with valves. A couple of questions:
1. Should I custom make a bracket or use a stock GT3 bracket or the Bursch GT3 exhaust retro fit bracket?
2. Any fitment issues anticipated?
3. Pipe sizing? Will going to the quiet port rob HP? Loud port only, will it drone? Should I valve it?
Thank you!