Hey, guys, today we're going to be taking a look at and installing the Roush rear valance
aero foil kit for 2018 GT Mustangs.
So, this kit comes in two pieces.
You have one piece that sits on the left side of the rear diffuser, and one piece that sits
on the right side the diffuser.
So, when you open up the box and take a look at it, it really doesn't look like a whole
lot, but as you guys can see, once you install it, it really does make a pretty big difference
in the overall looks of the factory rear diffuser.
This thing's also functional.
What it does is it directs and separates the air and keeps too much air from going in the
underbody contours of the car, which is ultimately going to help you with downforce.
So, you're really going to want to be checking these out for two reasons, one if you're looking
for a styling piece for a factory rear diffuser that's going to make a pretty big difference
in overall looks, and two, if you're looking for a functional piece that's going to help
in a racing situation.
These are made from TPO material, and they do have a grainy texture to them, which means
that they're going to fit in with your factory rear diffuser perfectly and look like they
belong there.
They cost about $140, and they install with both 3M tape and hardware, but the install's easy.
I'll call it a one out of three wrenches in the difficulty meter, and we'll show you how
to get it on the car now.
All right, guys, the first step of the install is to actually clean your rear diffuser.
These do install with both 3M tape and hardware, and once again, you want to make sure the
surface is going to be as clean as possible so your 3M sticks as best as possible.
The next step is going to be to take the supplied 3M tape and put a piece between each of these
bolt holes on either side.
We already cleaned our rear diffuser.
Once again, I'll say you want to make sure that it's as clean as possible so that your
3M can properly adhere.
So, we're going to grab a side, and these are side-specific, so make sure you're working
with the correct side.
We'll peel the backing off the 3M tape here, and we'll go ahead and get this lined up and
pressed into place.
So, these are contoured pretty well, so you know pretty much exactly where to put them.
Just want to make sure that I apply even pressure where the 3M tape is so it creates a good
bond.
We're going to leave this sitting here for now, until we can get some holes drilled.
And we're going to do the same thing on the other side.
So, we'll go ahead, peel the backing off the 3M tape, we'll get this lined up and pressed
into place.
All right, now we're on to drilling.
I have a 1/4-inch drill bit here, and what we're going to do is, we're going to drill
holes right here so we can mount our hardware.
I'm going to make sure that I hold the diffuser and that my holes are straight.
And we'll do the same thing on the other side.
All right, guys, now we're going to take the supplied hardware.
So, we have a bracket and we have two bolts here.
The bracket is threaded, and this is going to go inside our rear diffuser, so we're going
to go up over top of our rear diffuser.
We'll line the holes up and get our bolts in place.
All right, once again, we'll do the same thing on the other side.
So, we'll get our bracket up in place on top of the factory rear diffuser, line the bolts up
All right, now we're going to tighten these down with an 8-millimeter socket.
They don't need to be too tight, so just don't over-tighten them.
All right, the next thing we're going to do is take an 1/8-inch drill bit and drill three
pilot holes.
So, there are two dimples over here, Roush is telling us that's where we need to drill,
and then one back here as well.
So, once again, I'm going to hold the diffuser in place.
This hole needs to be much bigger than an 1/8-inch anyway, so.
All right, guys, now we're going to get our hardware in place.
These are self-tapping, so don't expect them to thread right in, and we have a 7-millimeter here.
And you're going to do the exact same thing on the other side.
All right, guys, that's going to wrap up this review and install.
Keep in mind that you can always check this kit out more online.
I'm Stephanie, and for all things Mustang, keep it right here at americanmuscle.com.