Big Block muffler choice

Im thinking I can get away with a 20" muffler, thats the body length. It would be like 25" including the in/out. Im looking now at the magnaflow and the dynomax. I have been using the V bands so no biggie on the disassembly/reassembly although Ill have to snip/weld for the longer body. If its still too loud Ill think about bullets. Space is an issue, but I flat bottomed the trunk and am running the shortened efi 68-70 tank so I have some room to play with. I was thinking that getting something that was 3"in and 2.5" out would be good but I already have the 3" pipe all the way back so since I feel like being fiscally responsible Ill use what I got.

If you care to weigh in, please post what length muffler body you are running. Most will be 14" on these floor pans Im guessing, but Im interested to know is anyone up in the 20" length? If so, how far forward of the axle is the body of the muffler? Or, is the body of the muffler under that low spot of the floor pan? (the low spot would be where the person in the back seat puts their feet.)

Thanks Fellas and Fellies if either of the ladies are reading. :poke::D:poke: