Jap speed exhaust modification or alternatives to make it quieter!!!

[doctor_tom]

Hi

I've been running a japspeed exhaust for ages and it's now to loud in the mornings.

The japspeed with twin cans and two 4" tailpipes.

I can cut the back boxes out and weld in different ones, has anyone done this? Which ones worked?

I can't seem to find any alternatives exhausts for a similar price.

If anyone has a quieter one. I'd happily swap.

[mr2garageswindon]

Do you have the bung that goes in the tail pipe? It does quieten it down quite a lot. I used one to get thru noise testing at the last track day I did. Took it from 102db to 94 ish db. Cheapest way of making it quiet.

[doctor_tom]

No I do not chap.

Sounds ideal as a way to keep the look but reduce grumble.

Where could I procure such an item?

[doctor_tom]

All sorted.

Bought two bungs for 9.99 each from ebay.

Bit concerned they are only 1.5" but it's something to start with and I can always weld in a 2" or something or a perforated pipe.

[mr2garageswindon]

Nice one

I've only got one and it makes enough difference in the passenger side pipe.
Try 1, try both, for that price its a cheap fix.

Happy neighbours too!

[doctor_tom]

That's good to know.

I have a 3" decat down pipe so should be a happy medium.

I'll pop them out on long journeys or for a bit of fun!

I'll polish them up too!

[Willenium]

Maybe have the 4.5" tips cut off and replaced with smaller diameter tips. Pop a bung into each and it should be a bit better.

[Race Idiot]

The tips wont make much difference in the sound, its more due to the poor quality baffles inside the two cans.

[doctor_tom]

The bungs won't help then?

I saw a post where a guy had added them to a japspeed and measured the noise with a microphone at a set distance and it dropped by 10-15 db.

The tips wont make much difference in the sound, its more due to the poor quality baffles inside the two cans.

[Race Idiot]

No the bungs will help! Modifying the tips wont however.

Only problem with bungs is that you restrict the exhaust flow a bit which robs you of a bit of boost.

[Nic]

The bungs won't help then?

I saw a post where a guy had added them to a japspeed and measured the noise with a microphone at a set distance and it dropped by 10-15 db.

The bungs will reduce the noise level but they are very restrictive and will noticeably reduce the performance. On a turbo running higher boost levels this could also significantly increase the exhaust gas temperatures.

You will get far better results (quieter and less restrictive) cutting out the silencers and welding in some decent quality ones eg. Powerflow, Jetex, etc. Generally the larger the silencer the quieter it'll be, if there's room I'd go with a couple of large oval silencers similar to the Berk exhaust.

[doctor_tom]

I'm only running stock boost, although it appears by magic my actuator has worn down to generate 12-14 psi which is perfectly fine by me as I don't need a boost controller.

I can weld in a couple of silencers but I couldn't find any, some are ridiculously expensive. I'm having a look around the odd scrap yard to see if any car has a suitable one.

Almost rather run with bungs to work and back, and just pop them out for a bit of fun.

The bungs won't help then?

I saw a post where a guy had added them to a japspeed and measured the noise with a microphone at a set distance and it dropped by 10-15 db.

The bungs will reduce the noise level but they are very restrictive and will noticeably reduce the performance. On a turbo running higher boost levels this could also significantly increase the exhaust gas temperatures.

You will get far better results (quieter and less restrictive) cutting out the silencers and welding in some decent quality ones eg. Powerflow, Jetex, etc. Generally the larger the silencer the quieter it'll be, if there's room I'd go with a couple of large oval silencers similar to the Berk exhaust.

[craig]

The bungs won't help then?

I saw a post where a guy had added them to a japspeed and measured the noise with a microphone at a set distance and it dropped by 10-15 db.

The tips wont make much difference in the sound, its more due to the poor quality baffles inside the two cans.

https://www.youtube.com/watch?v=-r3NpmTZxi0

However, I agree with above, and wouldn't run with bungs. Either fit a quieter exhaust or fit bigger silencers to the Japspeed.

[Race Idiot]

I was replying to someone else saying changing the tips on the exhaust wont make a difference! Bungs obviously will!

I met someone at bedford autodrome who had a japspeed with bungs in it, passed their noise test there so obviously does work. But they really aren't a longterm solution.

[doctor_tom]

The bungs won't help then?

However, I agree with above, and wouldn't run with bungs. Either fit a quieter exhaust or fit bigger silencers to the Japspeed.

Can you recommend some silencers that would do the job?

[craig]

You'd be better off consulting with an exhaust fabricator such as ExhaustsUK.

[Nic]

Magnaflow, Powerflow and Jetex all do 3" stainless steel silencers of varying sizes and shapes.

[doctor_tom]

Magnaflow, Powerflow and Jetex all do 3" stainless steel silencers of varying sizes and shapes.

Well at 150 quid each I doubt I'll be going down that road,

[Nic]

Magnaflow, Powerflow and Jetex all do 3" stainless steel silencers of varying sizes and shapes.

Well at 150 quid each I doubt I'll be going down that road,

I don't know how much space there is to play with but these may fit.
https://www.jetex.co.uk/jetexstore/oval ... 7600r.html
https://www.jetex.co.uk/jetexstore/oval ... 7600r.html

Another possible solution would be to cut open the end of the existing silencers and pack them with better noise absorbing material.