Muffler or no muffler - does it affect power ?

[SE_traveler]

On my 93 7.3 idi - previous owner told me he didn't like the loudness of the engine so he took it to a muffler shop and put a good muffler on it. From what I've read on this forum I wonder if this would cause a drop in power??

[VD350]

An engine is a giant air pump, the faster you can get it in and out the more power it makes. Yes you would loose power but I doubt it would be anything dramatic

[deanj]

Depends on what type of muffler. If it is a "straight thru" it should not.

[cdnsarguy]

This is one of the times less restriction equals more power.

[Mr_Roboto]

What I have found (with myself personally) is that the louder the exhaust is, the less useable power I have since I stay out of the throttle to keep the racket down. Also IMO it is harder to tune an engine when all you can hear is the exhaust and not the motor itself.

I wouldn't sweat the muffler, it's not like you can go out and buy a more restrictive muffler than what comes from the factory. The PO may have gotten the truck with a cheap aftermarket muffler or no muffler at all.