I know it has been discussed before but I am not sure if the answer is unanimous. Was the 2x4 carbs available as a regular option on the 401 or was it a dealer option? I have heard it both ways and I was also curious as to how it performed vs. the single AFB. Has anyone ran it both ways and compared it as far as driveability or power? I have been considering going with the setup but not sure I can justify it in my head just yet. The car seems to start and run very well as-is and I did not want to go backwards.