Very nice! What mufflers? Every time I film my car I never get the low end sound you got. It's there, just won't pick up with the phone. Need engine bay shots.
I just switched from a 434 SHP to a 421 Little M, with a little more cam, higher compression and better forged internals. She revs much quicker than my 434 did. Lighter billet flywheel is helping as well.
Here she is 3rd start, timing set. Just got her started this weekend after 4 months of down time swapping motors. Wish my video could capture the low end you have... Your car sounds monsterous.