Muffler types and the effect on power

[hotrod 80]

I wanted to open a discussion about this . I currently have Flowmaster 80 series SUV mufflers with cutouts . My machinist told me i could pick up 2 numbers by swapping to a Borla XR1 . I have bought the muffler , but im worried about the noise level . I work on the truck at the house alot and dont want to be a menice to the neighbors . They tolerate alot already . Anyway mufflers and power , open discussion .