blazer_4.3

i am helping a friend out, actually a guy i met recently and he dont have access to internet.
he a 97 cobra manual. bought it with flomaster muffler. he wants to get rid of that and put a better exhaust system on it.
i told him to go with x-pipe, but wasnt sure of the catback/muffer to put on.
other ? is i told him 4.11 gears would be a very good mod. last week he found someone to install them for him. who and what make should he go with? FRPP, i have seen that in alot of sigs.
i am gonna see him tomorow at the track and would like ot get this info to him.
all help is greatly appreciated.
p.s. by giving up this info u are helping out another ford owner. i think i beat him too many times and he wants things to be turned around!