Slant six in a Miata ? Why ???

Fans of Tony DeFeo and his YouTube channel "Uncle Tony's Garage" may already know of this build.....



I wonder though....Why put a slant six in one of those cars? Why not a V6 like a 3.6 Pentastar or an LA series engine?
Slant six...It weighs almost double what a Miata engine weighs and makes about the same power.
Tony had to hack the firewall, the trans tunnel and then butcher some bullshit cover to close off the engine bay and trans tunnel.....to fit a slant six in there.
Opinions?

Better than a LS...