My model of MX-5 is: 2016 1.5 Sport Nav
I am confused. The Mazda parts list seems to quote different Part Nos for the rear silencer for the 1.5 and 2.0 cars. However all the aftermarket rear silencers imply they are suitable for all models. So is there really a difference in the genuine Mazda ones and what is the difference?
I have the one for my 2.0 2019 back box going free if you want to pick it up it up from rugby its only done 1005 miles 
The one on the piece of carpet…..
Which two part numbers have you seen Ian?
I’m fairly certain it’s the same part, between 1.5 and 2.0 models.
What did you replace the OEM back box with ?
I have seen according to Mazda Parts lists
PE2R 40 100 for the 2.0 litre
P5C1 40 100 for the 1.5 litre
Thanks Ian, I thought it might be those two. I’d seen both of those part numbers too and what I’d found was the P5C1 40 100 was perhaps a sub-part number, potentially for JDM models. As to why they bother having two part identifiers, I couldn’t get to the bottom of that one!
I still believe both part numbers are interchangeable and compatible with either 1.5 or 2.0 NDs. There certainly weren’t two different parts diagrams I could find for each engine size.
Sent you a message
Hi, just brought a 2022 ND, looking at getting an aftermarket exhaust, whats the feedback on the Cobalt one ? good on motorway ? not too intrusive ? Thanks Steve
Cobalt is quite nice.
I’m going to list a Good-Win Super Street single tip soon though it will be about the same price used as a Cobalt new.
I have an “sports” after market back box fitted to my 2021 ND 2 Litre The same back box was fitted to my 2015 ND 1.5 Litre.
When I traded in the 2015 car the dealer wanted it returned to stock before they would take it off me.
I had kept the original back box so this wasn’t an issue. Anyone thinking of the same in later years might want to consider keeping hold of their original back box.
The original back box of my 2021 ND is in the loft having done 92 miles. 
This is the sports back box next to the original 1.5 2015 ND.
The cobalt back box looks like a popular upgrade. I haven’t read of any weight saving or performance increase only a more sporty sound.am I correct in this analysis and is the exhaust sound better?
Better is subjective, but it sounds sportier and people seem to be happy with them. There aren’t many if any back boxes that genuinely add performance without the rest of the exhaust being changed too and a remap. Just go with one that looks and sounds nice.
