I have a 2004 f250 with a 5.4 Lt I want to know what is the best muffler to buy I don't want to loose torque I tow a 30foot travel trailer
I have shorty headers on it ,a cool air kit and a power programmer

 

my mbrp sounds good

 

I put a flowmaster on my 08' with single inlet, duel outlet----love the sound---sounds like a HO mustang

 

I like my flowmaster 10 series.... sounds good at idle and it barks when I hit the skinny pedal. I didn't notice any difference in power after I put it on.

 

To be honest I don't know if there is a"best" muffler. If you ask 10 different people your likely to get at least 8 different answers. As far as I know there isn't just a plain muffler that will cause you to lose power in a 5.4. The factory y-pipe is very restrictive so opening up the exhaust has not given people negative results that I'm aware of. However you probably won't see any noticeable performance gains maybe 2hp and 4 tq type of thing. With that being said I used a Mac muffler and it sounds like an old muscle car, and I smile every time I start my truck or get on it. It's all about your own personal taste. It's more of a sound mod not really a performance one.

 

on my nephews 5.4 we did not run a muffler. the cat was enough to quiet it down.