Ive got a flowmaster 40 right now, and im getting tired of the sound and wanna switch to a magnaflow.
I want to keep it somewhat loud, but not as loud as the flowmaster, i just want a better flowing muffler, and a bit quieter cruising. I have a cutout, so being too quiet wouldnt be a bad thing.

 

well i have a 4x9 magnaflow,12 or 14 long i cant remember.I would go with a 5x8 with a longer length since you already have a cutout

 

BTW, running no cats and longtubes.

 

then I would go with the 22' length

 

5 x 8 x 22. i love mine. loud when you want it quiet when you don't.

 

5x8 oval here with a 14'' case.....my truck is bone stock beside the muffler and I really like it! Very mellow till you start mashin the pedal! But not too loud

 

Going with 5x11" here, 22" long dual in dual out Magnaflow case. A single in single out would be even quieter. The larger the muffler is by volume, the quieter it is.