New Exhaust requires a retune?

[joetiii]

I'm planning of replacing my stock muffler with a 2 in 2 out M+K for my 3.0 w/ PMOs. I wonder if the affects of reduced backpressure will require me to retune my carbs?

From what I've read, increased scavenging leans out a motor and may require the mixture to be fattened up a bit. Have any of you had to readjust your carbs after putting on a freer flowing muffler? or is this just required when you add headers?

[911pcars]

Outside of using other owner's set up specs, the most accurate way of knowing is to connect an A/F ratio meter to the exhaust. Chassis dyno shops have this equipment. You can also purchase a wide band sensor kit to monitor under all your driving conditions.

Sherwood

[Gene Wilkes]

Joe, the easiest way to proceed is to install the muffler, drive the car and see how it responds! If you have any issues like backfiring or bogging on acceleration, then you may need to adjust the carbs!