I have them with an o/r x pipe...and it is LOUD. (im 20 btw) I went from slp lm's with the o/r x to these, and ill tell you right now it isnt a HUGE difference. The o/r pipe really woke these up.

 

Love the sound, much better than stock or JBA's IMO... I'm just a flow guy I guess.

 

I have the American Thunder Series Flowmasters and I love them. They are not too loud, but when you get into the gas they sound good. The othere thing I liked about them is they are black and look stealthy under the rear of the car.

 

I've got the American Thunders on my Mustang and a pair of 40 series on my Marauder. I personally think that FlowMaster mufflers sound really good on these Ford modular V8s. The sound is perfect for me, and while I wouldn't mind it if they were a bit louder, I think quality of sound is more important than volume.

 

i have a 40 series on my 4.0 and i love it! yeah u do get some drone around 22-2300 rpm but the tone is great. plus it is pretty frickin loud. not as loud as an mrt but imo i like the tone better. i definatly recomend them. i plan on dynomatting my trunk very soon and that should take out the drone so ill let you guys know if it works!