"Hair Dryer `Trick" for making a second exhaust exit in the bumper?

  1. My model of MX-5 is: 2005 NBFL (Mk2.5)
  2. I’m based near: Portsmouth
  3. I’m looking for technical help or recommendations on: Modifying the rear bumper to make a second exhaust exit for a twin exhaust.

Hi everyone - I’m fed up of the muteness of my original Mazda exhaust (the sheer disappointment every time I enter the Hindhead tunnel with the roof down :disappointed:…) so am planning to fit something with a better sound this winter and, whilst I’m doing it, would like to go to a twin exhaust, as I’ve always wanted one and love the symetry of them.

When I was looking at the reviews for the MX5 Parts twin exit backbox (which is very reasonably priced, but looks like it may be a bit too far in the other direction in terms of loudness), I noticed a number of people have referred to the “hair dryer” trick (how apt! :haircut_man: ) for making the second exhaust exit in the bumper, instead of cutting a crescent out of it. In short they seem to soften the plastic and bend it into a more professionally finished exhaust exit with a finished, moulded edge rather than making a sheer cut in the plastic - sounds great, but I have no idea how they are doing it and can’t find any guides or you tube videos on it (and would like to do it now so I can get the bodyshop that’s doing my wings and sills to fix it if I screw it up!). It sounds like a much better option, but I’m worried about turning my rear bumper (the thing people spend most their time looking at when I’m driving :sunglasses:hehe) into a Salvador Dali painting!

Anyone tried this or seen it being done?

Thanks in advance!

Not sure if a hairdryer would be hot enough. May need a proper heat gun.

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bobsyeruncle - I had wondered the same, but they definately say hair dryer in more than one review… As it happens I have a proper heat gun in my garage, but definitely don’t want to unleash that on the car without some advice on how to do it (goodbye paint!!)

You’d end up destroying the bumper using a hair dryer/heat gun to bend and form the outlet.

They mean using a hairdryer to warm the plastic so you can use a stanley knife


I used a template from Racing Beat, and then a drill to remove the section of bumper, then tidying the edge with a sander.

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I don’t think that’s correct Saz9961:

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Don’t buy the MX5parts dual exhaust. Its what I have, and its bloody awful. Better off spending the extra on a better exhaust. I only fitted it because I thought I was going to sell this car. Intead, I ended up elling the other with the nice Mongoose exhaust. I’m kind of stuck with this now, unless I buy a new bumper cover.

Someone might claim to use a hairdryer to bend/stretch 4" of plastic out of the way, but I don’t believe them.

If it gets that hot to make the plastic pliable in a single spot without distorting a huge chunk of bumper, it will likely burn the paint.

After 25 years of MX5s, I have never heard of anyone using a hairdryer to remodel the bumper. Everyone cuts the bumper. Some take more time than others

As for symmetry, neither the NA and NB was designed to have such an exhaust. To get the pipes to line up, you have to faff around with various hangers, and put up with the exhaust knocking on bits of metal. I’m using silicone rubber hangers and a bit of zip tie bodgery, and it seems to be holding in place.

Let us know how you get on melting the bumper.

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Thanks Saz9961, and rest assured, unless I can get some guidance on how to do it properly (if it is even possible) I won’t be going anywhere near the back of my car with a heat gun or hairdryer!

I was thinking of getting one made made up by powerflow or the like…out of sheer curiosity though, why is the MX5 parts one so bad (in fairness, for the price I wasn’t expecting it would be fantastic). Is it just the noise or something else?


PS - zip tie bodgery or not, you’ve done a great job on getting that exhaust to sit well. It looks awesome!

The sound, the drone

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Ah - fair enough. That would really p**s me off too!

Out of curiosity have you tried wrapping your exhaust?

Again, I have no idea if it’s true but someone reviewed the exhaust and complained about the drone and then posted this some time later:

Don’t mess around with this. Just buy a Racing Beat system

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A few years ago I fitted a twin pipe exhaust to my brother in laws NB.
I cut the bumper carefully and it looked great with the twin pipes.
There was no jiggery pokery with cable ties etc required…

I used a multitool for cutting the bumper. Also used a conical crush washer on the mounting flange. This way you can make sure everything is lined up properly before tightening up the flange bolts fully & it should then sit nicely lined up.

Mine is a toyosport system & sounds about the same as the original one that came off.