muffler delete

Im looking into a few glasspack mufflers, i plan on getting a 16 inch muffler to replace my resonator, and then wanted to do and different glass pack muffler in the back but shorter would this work? and if so is stock piping 2.25” im interested is seeing what would happen muffling the noise...

ok so i know and have read the thread where backpressure and exhause velocity is discussed.....but yesterday me and my friend put a muffler delete kit on his 08 GT mustang......needless to say it made it loud as hell......the kit claims to add 5 to 10 hp...whether those numbers are true or not...