Resonator on an '02

Hey all, I have a quick questions. I have a second gen, but my brother has a first gen. When he bought it he put on a new muffler (I believe a flowmaster) he just had the shop point the exhaust straight down because he was too cheap to get the piping all the way to the back. Needless to say that thing is thunderingly loud, which he doesn't really like.
1) Would adding a resonator after the muffler help with the sound
2) What resonator would you suggest?
3) What is the piping size? 3"?

If this works out I'll be getting him this as a birthday present... unless you all say this is pretty much stupid.

I do know that piping all the way to the back of the truck would help the most with sound so no need to throw that suggestion at me

Thanks for your help!

 

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