I recently installed cutouts behind new headers when I rebuilt my 327. It runs 13.2 now with mufflers. I opened up the cutouts to try straight pipes and got no improvement, just a lot of backfires when I let off the gas.

Can I get advise on what carb and/or timing changes or tuning should be done to run straight pipes, assuming there is a benefit?

Many thanks in advance,
Steve M.

It probably runs a little leaner with the cutouts.