MMD rear diffuser

MANDARK said:

I think you mean Premium bumper because the PP also comes on base models. I know because I have a Base GT with the PP

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haha sorry... thats what i meant to say

I don't know what MMD was thinking when designing this diffuser, why the gap underneath this and the bumper? it catches air, dirt ,water. I was going to buy ,but Ill pass on this. MMD should have closed the gap and used the four mounting points on the stock bumper for a better fit.

With the crazy warm weather here in Michigan this weekend I pulled the car out from under the cover and pulled it outside to get a look at how things have been holding up.

I installed the updated version of this unit back in Nov in a climate controlled garage where the temp is a constant 60-65 degrees. The fit and finish is extremely poor and looks like A$$ on my car. You can see where it pulls away and you see the grey 3M tape. Even with a grey car you can still see the tape. This thing is an eye soar. Totally disappointed with this purchase. I fear removing the diffuser to try new tape will damage it since its so thin and poorly made.

Yeah that's gonna fail soon.

what a poorly designed diffuser , with the bad grey tape, the stupid gap underneath catching air , MMD messed this up. it do not look horrible, but a little plain. I wouldn't put this on my car. I'm going to paint the lower half of the stock bumper black , a lot of mustang owners are doing , and look really good. never mind this aftermarket junk

Can any other owners that have had this or still have this chime in? I may just bolt it down any way I have to.

Chameleon said:

Can any other owners that have had this or still have this chime in? I may just bolt it down any way I have to.

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Here is my opinion of it:


It's been holding up well! Although I replaced the crappy tape that comes with it for 3m black. And instead of the little plastic push pins, I drilled holes to fit in a 1/4x1" bolt with nuts.

So far it's been holding up well... done a 100mph a few times since I put it in there, and no signs of anything wanting to leave lol.

I guess the redesign fixed the issue... there is a little gap between the body of the car and the back of the diffuser since it is hollow that might create a parachute effect, but it looks pretty small. Might or might not fill that up with some foam.

The plastic used is a bit "thin", but pretty well shaped and formed. A lot of people give it crap, but don't realize that the plastic body panels on our cars are pretty the same thing in some areas lol. But then again, it is pretty thin.

The piece itself worth 200 bucks? Nah, maybe 100 (although my dad says the machine used to form those are expensive af), especially because I had to add a few things that should come with it in the first place. But hey, I got it for Christmas lol!

The looks worth the $200? I definitely think so. Looks like the premium bumper, but more aggressive for much less money imo... especially when you consider the cost of a premium bumper itself.

I got mine with the tape falling off. It literally peeled off the diffuser as I peeled off the backing. Obviously got rid of this junk tape.
I used VHB tape and the usual adhesive promoter combo.
That diffuser is not going anywhere without taking the bumper with it.
Also be careful cause VHB tape is a days work to take off if you choose to take it off.



My opinion of the value and build which is basically what everyone is concerned about:
It's completely BS that MMD doesnt seem to care about this diffuser anymore. I almost feel like this will be the last batch with the price drop.
(werent they 250)
Honestly the piece is worth 150 MAX with the proper adhesive.
It's not like they bought a machine to make this specific piece.



Yes it looks better than having base stock or even PP diffuser, but the rubber wear top feeling piece just isn't right unless you reinforce it.

So i let the tape weather. Its been raining here alot.
But this is what i did to the seams to make them waterproof and look better.
I used window screen spline.



How it looks just the tape Without the spline .


Half and half


Full spline



Bonus shot

chaospiece said:

So i let the tape weather. Its been raining here alot.
But this is what i did to the seams to make them waterproof and look better.
I used window screen spline.

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[MENTION=23457]chaospiece[/MENTION] that is a great idea. Will be pulling my car out of storage in the next week or so and will most likely be doing this mod

Can another vendor please make this but do it right? Without creating a parachute

This thing seems like an all around POS. It looks like everyone who still has it on had to modify it to help it survive

I see that this diffuser is on clearance sale on AM, i guess they had enough of this thing, even the so called newer ones are still falling apart ,Its odd that there is no guality made diffuser for the base mustangs, this mmd diffuser shouldn't even made it to market , just garbage

Made a few passes at the drag strip tonight and my rear diffuser is now junk. My rear bumper was also severally scratched and damaged in the process of it coming off the car. JUNK!

I have this piece installed. The tape it comes with was absolute shit. It was coming off straight out of the box. I replaced the tape with VHB black and also bought a 5 pack of 3m adhesive promoter. The biggest pain is getting the tape applied in one continuous piece without it splitting or stretching too much. If it splits you'll see the cut in the tape.

I prepped the bumper and installed the diffuser without too much fuss. So far it's held up to multiple high speed runs without falling apart or off. I do have one small spot in the tape which has come undone from the bumper, but it's not obvious unless you look for it. The diffuser does its job in the looks department.

Is it worth $200, hell no. Are there better options short of a full premium bumper swap ? No.

MMD is giving me a store credit. Better than nothing. Looks like I will attempt the Roush valance mod this time around.