- My model of MX-5 is: 2016 ND1 2.0L
- I’m based near: Southampton
- I’m looking for technical help or recommendations on: Exhaust fitment
Hi all,
I fitted a cobalt exhaust to my ND a month or so ago, but having some issues with noise.
When I swapped, I originally kept the donut that was on there as it looked in good condition. It was a little boomy but just figured it needed bedding in, so left it a week or so and put some miles on it. It didn’t improve, so I swapped out the gasket for the one that came with it. It seemed much looser on the midpipe side - the original fitted snugly over the protruding bit of the midpipe, whereas the new one seemed about 10mm bigger in diameter.
After another week, there was still no improvement and I could see water dripping out of the flange, so i ordered a new gasket. This one went on super snug. I also took the backbox off, as I had seen other posts of people that found a small lip in the flange that would restrict the movement over the donut. Sure enough, there was a small lip, so I ground it flush using a dremel.
Initially it was much better. Almost stock unless I put my foot down, absolutely perfect. Everything felt and sounded smoother, I could tell this was how it is supposed to be.
Pretty soon the boominess returned though. Under load it sounds quite sporty and nice but a bit raspy, maybe a little much (think EK civic!) but decelerating resonates super bad, it’s like being sat inside a subwoofer (top up or down).
Starting up in the morning is almost embarrassing until the choke stops and engine settles down to a proper idle. At idle it sounds almost stock.
Springs are tightened to just over a credit card gap, and the joint seems to move OK, but it is tough to get them together when fitting, as in i can barely get the flanges close enough to get the threads started before tightening down.
If I get under and give it all a good wiggle, I’ll sometimes get it sounding right again, but it just doesn’t last more than 5-10 minutes…
Any ideas? I’m 90% sure this isn’t how it’s supposed to be, and the brief quieter stints are how it should sound… I just don’t know what else to try.