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Discussion Starter · #1 · (Edited)
we have a problem in Netherlands en that's cars making more noise then 95db at 3500rpm. if its so they take your license plate and give you a minimum 270 euro ticket.

i have now only a kakimoto muffler and a silencer in it.
witch i don't think can reach over 90 dba.
the car is a r33 gtr as you can see in the avatar.

in short time there is going to be a replacements like a 3inch downpipe and a jap speed silenced decat.

my question is how many of you have the jap speed silenced decat and measure the exhaust sound?

please help. and sorry for my bad English.
i have to keep the sound below 95 db at 3500rpm after my changes.
 

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I run a Kakimoto Regu exhaust(92db) with kakimoto down pipes and a Sard high flow cat, and its nice and quite below 4k rpm, although its much louder higher up the rev range (its an R34 GTR Dyno's @440bhp, no issues with emissions or noise for national car test (NCT-ireland)
 

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Discussion Starter · #3 ·
that's good news for me mate.
my car is running the stock turbo's and i am planing to get them to 0.9 bar. around 420 hp with a new fuel pump an a nistune ecu. its only important till 3500 rpm. above that, they don't care. i know that the jap speed decat can reduce the sound like 10 db.
so with my setup plan it should stay around 90db at 3500 rpm i hope.
 

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Discussion Starter · #4 ·
i have this one. dont know wich type it is.
any one else to tel more about the jap speed silenced decat?
 

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Discussion Starter · #7 ·
thanks for you advise Matty,
this type of exhaust is unfortunately no go for me. every year i have to put the oem cat, back in its place. otherwise cant get the mot. japspeed decat is easy to replace ans i already bought the 3inch downpipe and the kakimoto muffler.
i need to hears some decibel numbers from people who has the japspeed silenced decat.

worse case scenario i drive around with my muffler silencer in it.
 

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My car with Blitz Nur Spec-R exhaust, Trust downpipe, HKS elbows and a pair of Garrett 2860-5's with a Japspeed silenced decat was 93db at 3500 revs but got me black flagged once out on track at Castle Combe!:D
 

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thanks for you advise Matty,
this type of exhaust is unfortunately no go for me. every year i have to put the oem cat, back in its place. otherwise cant get the mot. japspeed decat is easy to replace ans i already bought the 3inch downpipe and the kakimoto muffler.
i need to hears some decibel numbers from people who has the japspeed silenced decat.

worse case scenario i drive around with my muffler silencer in it.
bit confused so what your after is a slicenced decat? or sports cat?

or basically a bung
 

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Discussion Starter · #10 · (Edited)
I need better flow.
i have now a 3 inch downpipe, oem cat and 3 inch muffler. i only need to change the oem cat to a decat for the stage 1 setup. every year i have to change the decat with the eom one to get the mot. And like i said the police is checking cars for there exhaust noise and if its to loud i will have a big problem. that's why i am choosing a quiet decat that can be removed when its need it to. so how quiet is the silenced decat?

i have to keep it as quiet as pussble. i have already a 3+ inch downpipe and muffler and the new decat must make it nice and quiet.
so basicly i am after the silenced decat. if more people can tell how good or bad the japspeed silenced decat is?
 

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i have it on mine but i had to remove the kakimoto as it was too loud but on my fujist- something exhaust it lowered it alot around 20db at a guess but it was quite obvious
 

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Discussion Starter · #12 ·
so, kakimoto has to go to?
it is a very loud muffler without the silencer in it.
or i have to drive around with the silencer.
 

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Discussion Starter · #13 ·
now i am confused.
is it better to go with a silenced decat and my kakimoto muffler or just a cheap decat and a good quiet muffler?
 

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Discussion Starter · #14 ·
I have fitted the Silenced decat and boy what a difference.
I want to thank Paul (Japspeed) for the fast service.
i have not test the DB's yet but i can tell you that is now quieter then before with the oem cat.

 

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Thread revival (sorry) I'm gonna be looking at one of these japspeed decat pipes altho need to get a bung welded in for the wide band sensor. Need to see if it's something they can do

Sent from my SM-G920W8 using Tapatalk
 

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It seems to have dropped a few db for ppl with hks and minimised the drone tho so I think it's worth me doing.

Sent from my SM-G920W8 using Tapatalk
 

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I have one fitted and I felt it very slightly reduced the noise but more importantly cut some of the drone at motorway speed. I have a trust downpipe with HKS Silent cat back.
 

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I have one fitted and I felt it very slightly reduced the noise but more importantly cut some of the drone at motorway speed. I have a trust downpipe with HKS Silent cat back.
Nice one. V similar to me then.. Mines downpipe and hks silent power which is anything but. Yeah that mway drone is what winds me up mostly so if it minimises that and doesn't go crazy with my tune then I'm happy

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