I would call the guys at Banks, They'll know what your particular engine suffers
Adding a Catback without intake modifications may cause problems. My 5.7 had
poor flow on the
intake, and the stringer intake from banks had a noticable improvement by
itself. But tthis may not
be the case with the 5.3.
i was thinking of using a 2 1/4 inch duel exhuast, with a h pipe. to get
specific about the setup's my freinds have had problems with, one freind
has a 3" cat back mandrel bent with a 40 series flowmaster on his 4.3
reg/cab s/b. i went for a ride in it before and after he had his exhaust
done, and there was a noticeable loss of power through out the rpm band
lost botom and top end...... another freind 5.3 reg/cab s/b, just
replaced muffler with flowmaster also complained of lost power. and a
couple other guy's i've asked at the local 1/4 mile track have said the
same. just dont make sense to me any help would be appreciated.