Chevy Gm LS1 LS6 12V High Output E-Poxy Ignition Coil Red [Square D585] 8pcs The main difference is that

The main difference is that there is an open area under the plenum chamber

it has a square bore carb flange instead of a spread bore

and regulator

They're designed with performance in mind

Chevy Gm LS1 LS6 12V High Output E-Poxy Ignition Coil Red [Square D585] 8pcs The main difference is thatFailure or poor performance from a coil can result in a misfire, a rough running, hard starting engine, and excessive emissions. Speedmaster's ignition coils provide the performance needed to help keep vehicles running the way that they were designed. These coils have corrosion protected laminations to protect coils from the harsh operating environment