This article is from the Toyota Tundra FAQ, by Steve Yee with numerous contributions by others.
The Tundra ignition system is a very unusual one that doesn't modify very well.
The reason for this is that each cylinder has an individual ignition coil.
(The V-6 has an ignition coil for every two cylinders.) The only known
modification for the Tundra ignition is the MSD "Stacker" ignition system,
which piggybacks onto the existing system to provide a multiple spark setup for
specialized modifications such as supercharged nitrous configurations. The MSD
part number is # 7020.