Fat Boy 4 Complete Exhaust System Yamaha YFZ450R “STD”
Part Number: FB4-EY345R

DRI offers a LIFETIME WARRANTY against defects in materials and workmanship on all Fat Boy 4 systems sold. Warranty is for original purchaser only and is non-transferable. Each
system is supplied with warranty registration card that must be read, signed
and returned to DRI.

Product Information: Fat Boy 4 STD Pipe

Model: 2009-2021 Yamaha YFZ 450R

Price $699.00

Performance: 7+ HP Gain when tuned properly and
used with an upgraded air filter kit. Power emphasis is Bottom and Midrange.
Rideable Smooth Power

Other Required modifications:
-Air Cleaner Upgrade: Pro Flow Air Cleaner with K&N Air Filter, Feul Customs Intake System
-Vortex ECU. Air Fuel must be adjusted for proper performance and reliability
-Larger C/S sprocket advisable in hard pack terrain or on with 18" tires.

Fat Boy 4 Features
-CNC Bent 304 stainless steel headers, mid-pipes and tail sections. Standard finish; brite finish.
-CNC machined stainless steel header flanges.
-Custom designed .100" wall aluminum extrusion muffler body. Standard finish satin. Polished by special order.
-Front and Rear End Caps CNC machined from 6061 billet aluminum.
-Muffler mounts CNC machined from single piece of 6061 billet aluminum and attached to muffler body by heli-arc weld.
-O-Ring Seal at tail pipe to muffler joint.
-All mufflers completely rebuild and repackable.
-Stainless muffler cores.
-Optional (at additional cost) Bolt On Turndown; redirects exhaust fumes and noise toward the ground. Also required for use with spark arrestor. Attaches with 4 stainless screws (supplied) and has O-Ring seal.
-All systems are individually marked with their own serial number.
-Complete DRI Technical phone support for installation and tuning questions.

Optional Accessories
Custom Color Mufflers and End Caps Available call for details
Turndown $39.95
Fat Boy 4 Replacement Packing $29.95
Fat Boy 4 Rebuild Kit A $64.95
*includes: packing, screws, o-rings, thread lock, decal, instructions
Fat boy 4 Rebuild Kit B $39.95
*includes: packing, screws, o-rings, thread lock, decal, instructions

Fat Boy 4 4-Stroke Power Exhausts are a proprietary product of Duncan Racing International, Inc.
DRI is the sole manufacture and developer of this product. DRI has designed
this product to be the top ATV 4-Stroke exhaust on the market.