So after some research I removed my Flowmaster 40 series to replace it with a new stainless Magnaflow. My truck lost its rumble and is much quieter now. This is not what i wanted, I thought the straight through design would have been a little louder . Both mufflers are 14" long and are SIDO 3" inlet and dual 2.5" out. Just sending this info out there for anyone who needs it. Also didnt notice a change in either power or responsiveness.

 

Add high flows... louder. My truck sounds better than any chambered muffler I've heard. And straight thru's are louder than chambered on WOT

 

combine them and make a magna-master muffler

Revolutionary chambered flow through muffler!

I like my FM knock off.

 

yeah, i dont understand the flowmaster hate on this board. but give the maggie some time to break in it'll get more noticeable. probably not as loud as the flowmaster though

 

I still have the stock cats (4) on my truck though. I was worried about putting high flows on and causing CEL. PA emissions testing is strict. Any advice??

 

yeah, if you are gonna mess with them replace all four (4) cats with two (2) maggie 94106 high flows.

 

thanks for the heads up quieter is definately not what I would have expected either.

 

I've had both on my truck and the Maggie has less drone then the Flow 40 and sound's deeper when accelerating. Also the Flow 40 rusted out in 3 year's. The Flow 40 was louder at idle and when hammering down but not by much!

 

You should have bought a round body Maggie instead of an oval body if you wanted loud and aggressive. Cut the rear cats off to make your current Maggie sound better.

If you want to learn more about cats and general exhaust knowledge, check out "The Exhaust Guide" in the exhaust section.

 

I have also been doing the exhaust debate and after much research I will be switching out my Flow 44 SI/SO 3" to 4" tip to some Dynomax Bullets for more and deeper noise. You need a race muffler like a Bullet or Magnapack.

I also have all 4 stock cats on my truck. Going to replace with true duals with an X pipe and 2.25" pipe and do it 45'd out each side in the back with some 4x18" magnaflow tips.

Depending on the exhaust not I will cutoff the rear cats as the 02 sensors are BEFORE the rear cat and the front cats function as a Hi Flow cat. You don't need to add hi flow cats, just remove the rear cats and weld up a pipe. You will not throw any check engine lights etc as all 02 sensors stay in their stock locations and are BEFORE the cats you removed. Will deepen up the note.

Only thing you need to worry about is passing emissions if you have them. Wont be a for pollution but it would fail a visual inspection if they realize the previous-early 05 F150's have 4 cats and the late 05-current only run 2 cats.

Hit up DarrenWS6, Mblouir (Matt) or 4.6 Punisher above and see if they can give you any advise on how to deepen up the exhaust note to get what you are looking for. They also have quite a few videos on Youtube where you can hear the exhaust note and 4.6 Punisher has an amazing sound to his 4.6.

 

Great thread, I'lkl keep my FM and ditch the cats in favor of better flowing cats.

 

The cats make a big difference. I think I'm leaving mine alone for now until I go with my big $$ set-up years down the line. The high flow cats made my truck deeper and much louder and it has a unique sound.