I'll show you how to add dual straight pipes on a Freightliner Columbia or Century class.

Parts:

Y pipe:
P/N 0417129009

Flex pipe:
P/N ABPN495FT18S

5" Clamps:
P/N ABPN3550PLS

45° elbow:
0417555000

Bracket:
https://www.raneystruckparts.com/pete...
Clamps:
https://www.raneystruckparts.com/pete...
Bushings:
https://www.raneystruckparts.com/pete...

Hardware:
Exhaust Clamp:
8 hex head bolts 3/816x2.25 L Inches
8 hex nuts 3/816
16 flat washers 3/8 I.D. x 7/8 O.D.
8 lock washers 3/8 I.D.

Exhaust Bracket:
16 hex head bolts 3/816x1.25 L Inches
16 hex nuts 3/816
16 flat washers 3/816x7/8 O.D.
16 flat washers 3/8 I.D. x 1.25 O.D.
16 lock washers 3/8 I.D.