Flowmaster X-PIPE 81107 User manual

409S®Stainless Steel
This X-pipe assembly is designed to be used with either the factory mufflers or a Flowmaster axle-
back system. The steps on the following two pages are intended for customers replacing the center
resonator of their vehicle and retaining the use of the factory Mustang mufflers. If you are using the
new Flowmaster X-pipe along with a Flowmaster axle-back system, please see pages 3 thru 5 below.
10/10/16
Removal:
1) Raise the vehicle up on a hoist or rack to working height. If you don’t have access to a hoist or
rack, raise the vehicle and support securely with jack stands. To ease the removal of the stock
system, spray a penetrating lubricant onto the bolts of the two clamp connections just forward of the
center resonator.
2) Begin by measuring back 2 ½” from the beginning of
the straight area shown in the photo at left and make a
mark on both pipes. Support the exhaust system both in
front and behind the area to be cut. Check that the marks
are correct, then using a sawsall, cut both pipes at the
marks. Note: Due to the closeness of the pipes to the
gas tank, use caution when cutting! Carefully deburr the
end of the muffler inlet pipes where cut with a file or die
grinder.
Pg 1 of 6 Technical Support [phone]
Installation Instructions for:
X-PIPE #81107
2015-2017 MUSTANG
3.7L · V6 ENGINE
Fits Fast-Back and Convertible Models.

3) Support the center resonator with a stand and loosen the four nuts at the two band clamp
connections at the resonator inlet. Using a screwdriver, pry up the clips on the clamp body to release
the clip from the tab on the inlet pipes. Slide the clamp assemblies slightly back to clear the tabs. You
can now lower the rear of the resonator and slide the assembly to the rear of the vehicle to remove.
Lower the resonator from the vehicle and set aside.
Installation:
1) Slide a supplied TB810Sadapter pipe onto the
end of each outlet of the 86348 X-pipe assembly.
Place a supplied clamp onto the connections and
tighten enough to hold.
2) Remove the factory band clamps from the factory exhaust system and place them onto the
downpipes behind the catalytic converters. Place the 86348S X-Pipe assembly into place behind the
factory downpipes, support the rear of the assembly with a stand. Slide the clamps back to the bump
stops on the X-Pipe and tighten both band clamps enough to hold, but still allow for adjustment. Be
sure that the X-Pipe assembly is fully forward, and that the embossed Flowmaster in the center case
is facing the ground before tightening.
3) Place a supplied clamp over the inlet pipe of the passenger side stock muffler. Slide the
muffler toward the rear of the vehicle and place the inlet into the adapter at the back of the X-Pipe
assembly. Slide the clamp onto the slip connection and tighten enough to hold in place. Repeat this
step on the drivers’ side of the vehicle.
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4) Adjust and level the X-Pipe and muffler assemblies to provide a satisfactory fit. A minimum of
1/2” clearance around all parts of the system must be maintained; while keeping suspension travel
and vibration in mind. After adjustments have been made, you may now securely tighten the
clamped connections.
5) For a more secure installation, we highly recommend placing a minimum 1” weld on either side
of the inlet slip-fit connections.
The following instructions will describe the steps required to install X-Pipe assembly #81107
with a Flowmaster Axle-back system.
Removal: 01/04/16
1) Raise the vehicle up on a hoist or rack to working height. If you don’t have access to a hoist or
rack, raise the vehicle and support securely with jack stands. To ease the removal of the stock
system, spray a penetrating lubricant onto the bolts of the two clamp connections just forward of the
center resonator as well as the rubber hangers just behind the rear differential and at the rear of the
vehicle.
2) Place a stand under the center resonator just forward of
the axle-back muffler assemblies. Loosen the clamps at the inlets
of the Flowmaster axle-back mufflers.
3) Using a 13mm wrench, loosen the two hangers just behind the rear differential from the cross
member and the two hanger mounts at the rear of the vehicle from the frame. Slide the muffler
assemblies toward the rear of the vehicle to disengage them from the factory system. Leave them
hanging in place for re-assembly onto the Flowmaster X-pipe assembly.
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4) Loosen the four nuts at the two band clamp connections at the inlet of the center resonator.
Using a screwdriver, pry up the clips on the clamp body to release the clip from the tab on the inlet
pipes. Slide the clamp assemblies slightly back to clear the tabs. With the help of an assistant,
carefully lower the stand and slide the assembly back to disengage from the inlet pipes.
Installation:
1) Remove the factory band clamps from the factory exhaust system and place them onto the
downpipes behind the catalytic converters. Place the 86348SX-Pipe assembly into place behind the
factory downpipes while supporting the rear of the assembly with a stand. Slide the clamps back to
the bump stops on the X-Pipe pipe and tighten both band clamps enough to hold, but still allow for
adjustment. Be sure that the X-Pipe assembly is fully forward, and that the embossed Flowmaster in
the center case is facing the ground before tightening.
2) Place the inlets of the axle-back muffler assemblies onto the back of the Flowmaster X-pipe,
be sure to slide them fully on and tighten the clamps enough to hold, but still allow for adjustment.
3) Adjust and level the X-Pipe and muffler assemblies to provide a satisfactory fit. A minimum of
1/2” clearance around all parts of the system must be maintained; while keeping suspension travel
and vibration in mind. After adjustments have been made, you may now securely tighten the
clamped connections.
Pg. 4 of 6 Technical Support [phone]

4) For a more secure installation, we highly recommend placing a minimum 1” weld on either side
of the inlet slip-fit connections.
PACKING LIST
Qty Description Part#
1 X-Pipe Assembly. 86348S
1 Hardware Pack PK812
2 Adapter Pipes TB810S
4 2¼” Clamp MC225BS
Pg. 5 of 6 Technical Support [phone]

Installation diagram for:
X-PIPE #81107
2015-2017 MUSTANG
3.7L · V6 ENGINE
Fits Fast-Back and Convertible Models.
Technical Support [phone]
409
S
® Stainless Steel