Getting a more muscle sound out of a 6

That is the principle reason why a slanty can never sound like an SBM. When you separate a V8 into duals, you get the patented Harley-Davidson 5-7 back to back firings out the left pipe. Whereas slantys with duals fire a steady rhythm .
Slantys are;
bloop-bloop-bloop-bloop-bloop-bloop-, 1-5-3,6-2-4
bloop-bloop-bloop-bloop-bloop-bloop
V8s are;
rump-rump-rump-rump-rump-rumpidy-rump-, 1-8-4-3,6-5-7-2
rump-rump-rump-rump-rump-rumpidy-rump
Additionally at 700 rpm idle, a V8 fires 2800 times per minute, whereas the slanty at 550idle fires just 1650 times.The slanty would need to idle at 933 to match the 2800 pulse-count. And then it sounds really busy without the "rumpidy"