hookedonboost

Good morning,

I was wondering if anyone has made the following change and can let me know if it helps with the dreaded drone!

I have a J's Racing 70RS twin system using the J's Racing 63.5mm de-cat pipe, I checked and J's Racing only make a standard sized 63.5mm de-cat pipe. I was wondering if these two different sized pipes can affect drone? I was considering changing the current de-cat pipe for a 70mm pipe which would be the same as the exhaust but feel it strange that J's Racing would not make a 70mm if they felt it better? Perhaps in a racing situation they don't care about drone. Has anyone moved from these pipes on this exhaust and noticed a reduction in the 3-4k drone?

flanders

They do make the 70RR system that is header and back, probably their best choice for racing use
Don't think you would notice much difference changing from 63 to 70 though, performance wise 70mm would ofc be better.

hookedonboost

It was more the drone that I am looking to reduce, I worry about my hearing around the 3-4k mark and my driving is not all motorway so have to use this range every day.

CHIPPO

Ha ha , the old drone conundrum .

If you don't want drone why buy an aftermarket lightweight racing type exhaust , it will drone , it lacks the design input to prevent drone , items that add weight , such as Hemsoltx resonators , complex back boxes etc that Mr Honda spent ages and lots of bucks sorting out for a nice civilised noise profile .

I have got rid of an HKS that was truly awful and to be honest not sure why I bought the dam thing the drone at 3 k was painful , but of course if you drive at 10 tenth all day it's fine , any way welded up my old OEM , did the Uk mod with 32mm , no drone and nice noise above 6k

If you look at the OEM yes it's quiet , but it's heavy , it's complicated and hence no,drone , so the choice is yours

The Hemsoltz resonator issue needs lots of research , but often used (OEM has one) to prevent drone a common problem with aftermarket exhausts there are lots of internet comments about these from the states where it is,often a,problem,with trucks and such like where the good old boys stick on nice noisy pipes and land up,deaf ( not,really ) but then have to mod them to make them useable
.
These sodding aftermarket companies don't give a fig , they just knock something up and sell it to us know on average no one is going to complain as the young men love a bit of noise .


research. It did tends to suggest a Hemsolts about 28 inches long for a four pot engine with drone at 3k but there are lots of variables to add in and it would be trail and error to get it spot on.

hookedonboost

Yeah I thought I could handle it but as a daily drive it just seems to much, the de-cat pipe helped compared to the stock cat as that was seriously loud drone, this is what made me think playing with the size of the de-cat might help! I did like my UK Mod standard system, I had a 44mm bypass and sounded great, I just wanted to change the look and save some weight versus the standard system. I knew power wasn't going to be increased but I just wanted to try to reduce the drone getting a new de-cat pipe.

flanders

My T1R 70R-EM single system is actually almost completely drone free with a 70mm test pipe.
I got a 70mm high flow cat on now and it's makes a slightly annoying drone at around 3500rpm under load.
It's not that expensive getting a 70mm test pipe so it might be worth a try but don't expect miracles

CHIPPO

I am thinking of trying chopping the tail pipes of off My back boxes and welding on stub pipes of SS. Around 90 diameter to get the look of an aftermarket , cut of at a slangy angle they might look ok , maybe even blue the tips a bit . Have to be careful though as the tail pipes have small kinks in them to get them to exit straight.

I think a young mans perception and acceptance of drone is some what different to an old fellas !

flanders

Not sure if 34 is old enough to have a low drone acceptance?
It's actually sold with the marketing that "there is NO DRONE in the exhaust sound" and there are some vids that kind of backs it up as well.
http://www.evasivemotorsports.com/mm...-INTAKEEXHAUST

CHIPPO

Well there you go young man , sale of goods act " not fit for purpose " lies and dam lies get your bloody money back.

I wish I had done this to xxxxx and HKS , all these purveyors of crap design poorly manufactured exhuast systems need to be brought to book . They are ok for racing and little else where the car runs at or near the red line and not normal driving.

CynicG

I have to say my HiPower Silent is very acceptable Chippo, and I thought the 304 version was supposed to be louder. I don't know, maybe its the other mods having an effect on flow, but I can't fault it. Stock on low revs, a hum on 2.5k with no throttle, and aggressive @ WOT. I agree some aftermarket kit is noisy as hell, but there are a lot of parameters to factor in.