Hi all

2001 F150 Screw 5.4, NO cats.
My buddy had a Roush catback system on his 2011 F150 that he took off when he traded the truck in, and I ended up with it.
After some mods, the shop got it installed into my Screw.
The system has a resonator and the single pipe exits the resonator and goes into dual tips.
I really enjoy the growl, but it needs to be dialed back in overall output some. It can be heard from a mile away when really stepped into.
My question is, can I just have the shop put a muffler into the system somewhere, before or after the resonator?
If so, what kind of muffler do you guys recommend? I have a Flowmaster 40 series just sitting around that I had took off when they installed this system.

 

I'd recommend you put a pair of high flow cats on it.

 

x2. If you refuse to, add a thick round body muffler to the intermediate pipe.