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Exhaust to loud

As title says my exhaust is to loud. I need to make it quieter for track days as I’m pretty sure I will get black flagged for it.

Car is a 172 ph2 running a decat 2.5” exhaust and power flow backbox. Reason I went with the power flow was because of its size and having it exiting through the centre I didn’t want something massive. I will also add the car does also have a mid silencer. What are my solutions as don’t really want to be changing my exhaust system as i have custom made it all.


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No standard manifold, decat 2.5” exhaust with silencer and power flow backbox. I’m in 2 minds whether to cut the the rear silencer open and pack it out abit? I’m not sure to be honest just need it quieter!🤣

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On an app which I kno probably isn’t the best idea but I used it at the time because I knew it was louder than my old exhaust

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ClioSport Club Member
For reference mine is 103db static, 2.25" Janspeed system with no mid box, 2.5" de-cat, 182 manifold (which is usually louder from experience).

Go down to the track when they have a day on and get it tested with their equipment, best way to know what you're working with.
Thanks for the advice guys I’ll report back with what I do to rectify it hoping to do another track day soon at Donington so I’ll keep you all posted

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ClioSport Club Member
You will need to add a bigger/better silencer or another silencer to drop the db level if you dont want to refit cat. Powerflow back boxes usually dont do much. Im in the same situation with my kangoo, one large rear silencer with stealth sytle tip but still very loud 99db static.

Nathan Evans

ClioSport Club Member
I doubt it’s louder than my old exhaust. I only had a problem on one track day. The exhaust was custom made with decat, no middle silencer and tiny back box. I only got flagged at Donington on a quiet track day.
For the rest of the day I had to let off down the pit straight and it was ok the rest of the day.
Oulton and Anglesey it was fine.

Now I run the same decat match up to a 2.5 pms exhaust and it’s a little quieter. Even with intercom when your flat out it’s hard to hear


ClioSport Club Member
Donnington is always s**t hot for noise, I got black flagged going 98.3db on the main straight in my Extra van a few years ago. I think the key is to lift a bit on the straight in something thats borderline noise wise. Not been back since prefer Cadwell - no bother there pass 105db static and away you go.