After 500 miles, I decided it was time for a change in my new '04 Screw 5.4 Lariat.

I went to a local mufler shop in San Diego (Dualtone) and they sold me a Magnaflow SI/SO 18" #11256 for $180 out the door using my own pipes. It's just not loud enough. There's no drone, no popping, and no sound. It's much smaller than the OEM but sounds just slightly louder. Better flow and probably more HP, but I need the sound.

I had an '02 Screw 5.4L and put on a Ravin Z55 with AirForce One, Chip etc. and loved it. Why I didn't do the same thing? Low end power loss with the Ravin but Great sound.

I'm headed back to the shop for either a Flowmaster or to Midas for a Ravin Z55.

Any suggestions? (FM 40 or FM 40 Delta or Ravin)

JM - San Diego

 

Get a shorter Magnaflow. Remember, the '04s are quieter inside, too.

 

chop off a couple cats

 

The smaller the chamber, the louder it will be. Try a smaller Magnaflow.

 

straightpipes- period

 

He's right. If you want it loud, let the cats be the mufflers. Replace the muffler with a straight pipe. If not anything else, use that as a baseline for 'sound'. What I don't know...is if you need the back-pressure the muffler provides to make the cats work.

 

I'm just now learning just how restrictive cats are. Are there converters that are free flowing and still legal? Anything out yet that's nice for the '04 SCREW?

Has anyone tried the original Flowmaster 40? You can pick them off Ebay for under $60 delivered.

Thanks for the help.

 

Be careful about changing out the cats in good 'ol California. If they are not damaged or malfunctioning they cannot be legally changed out. If they are, then you can change them with high performance ones. If you remove them illegally, I would hate to see you go into a smog check and they look and see different cats or no cats and them not passing your smog on the visual inspection. You would then have to put the cats back on to your truck. Plus you are not going to pick up any really noticable gain in power until you are supercharged to warrant a high performance cat.

As for the muffler issue, I don't like Flowmaster because of their design, the exhaust keeps hitting walls till it can go through the muffler. I am partial to the Borla sound. I have a dual Borla 18" setup on my 54 F100 and love the docile but sweet idle and the killer full throttle roar. Most flowmasters kill performance but sound great, I prefer a good sound with good performance. I would go with a shorter magna muffler to get more sound. You should look at a 12" muffler if you want sound.

Brian

 

I think I'm going to hang onto the OEM cats to keep things legal. I'm off to the muffler shop for a shorter version of the magnaflow.

Thanks for the heads up, I'll let you know how things go.

 

how about posting a sound clip of "before" & "after"?

 

I'll do it this week and get it online.

The sounds will be: Before (non-stock Magnaflow 18") and after shorter Magnaflow or ????

The muffler shop in San Diego could not have been cooler. "No Problem, just bring it in".

 

The change is done.

I went back to the muffler shop today where I had the Magnaflow installed and they cut it out. In it's place is a new Flowmaster Delta Flow 40 series. They charged me another $75.00 but it was worth it.

The verdict...the sound is much better with no power loss noticed at all at any speed. The sound is WAY better and I like it. More low end rumble but not too loud for the neighbors (who cares about the wife).

That being said, I think I would go back with the Ravin Z55 from Midas next time. I had it on my last Screw 5.4L and the sound was awesome.

I kept the stock pipe for now but I may go with a custom 3 inch pipe from the muffler back for an even more free-flowing system.

Next stop, leveling kit and bigger tires and wait for the Airforce One.

JM