Ok so iv got this great deal on a flowmaster 10 and i want to put a glass pack behind that for a deeper sound. is this needed? I only want a deep sound no drone or anything. this will be from the last cat and hopefully come out for a side exit

 

The Flowmaster 10 is pretty aggressive on it's own. I'd try it on it's own first.

I don't know what adding another muffler behind that would do, if anything. Glass packs are cheap, so I guess it wouldn't be too hard to try it out though. Maybe one would act like a resonator.

 

A small glass pack I doubt will change the tone much.. Probably some but more likely just tone done the loudness like a resonator.