NAforever

Hello,

I've just installed a borla catback and after 600 miles, drone appears to be obnoxiously loud.
I measured 90 db inside the car at 2000 rpm on slightly load with the iphone application decibel 10th.
I readed many posts related to drone and it seems to be black and white: Someone has no drone and other have.
Feeling is subjective but 90 db is not!
So, is it possible that the way of installation could dramaticaly conditionning drone?
I think for example at torque tightening bolts, alignment, tip alignment and distance between mufflers output and exhaust tips...

Sean

iTrader: (3)

It's possible since a bad exhaust leak can cause what you're describing. 2000 RPM will drone though, even if everything working correctly, but it shouldn't be as bad as you are describing.

caveman

i'm not an exhaust install expert, but unless you have an exhaust leak at one of the slip joints, i dont think slight variations in alignments will affect the sound in any material way.

it would be interesting for comparison if any of the other members who recently installed the joe-z catback can measure the db from inside the car @ 2000 rpm and see what the reading is.

NAforever

I inspected the slip joints and no leaks at idle. I don't see any soot.

flowrider

iTrader: (9)

^^^^You spot an exhaust leak, by curving your hand had rotating it about a quarter inch or so around the all clamp areas. Leaks are sometimes hard to find.

In any case, a leak would not cause the drone that you are experiencing. The natural harmonic for drone of the ISF engine is around 2K RPM, exactly where you are hearing it.

A leak would just make loud exhaust noise hearable inside and outside the car, and not be RPM dependent.

Lou

BLKLBL

I recently installed a borla catback on my isf also.. I have about 600(kilometres) on mine.
I have the decibels app for the iPhone also, I'll take a reading at 2,000 rpm and post results.....

NAforever

Lou,
That's exactly what i did to search for leaks
Yes it's a problem of harmonics and that's why i suppose tightening and adjustement could also influence drone.

Thank's BLKLBL!
some "scientifics" comparaisons could be good.

I8ABMR

The Joe Z drones pretty good at 2k also but has been getting quieter literally every time I drive the car. I love everything other than the drone BUT the stock system droned also. If its new Im sure it will mellow with time.

NAforever

Yes, the oem exhaust drones but with the borla catback on my car the difference is tremendous!

BLKLBL

I measured just less than 80db at 2,000 rpm with slight engine load.
At very light engine load, it was around 78db. At heavier engine load going uphill it was around 82db.
At idle, 65db.

I8ABMR

90 db is crazy. They run a track out here where the limit for noise on the track is 93 db and that under full load on some of these track prepped cars

Meraki Autoworks

iTrader: (8)

I think its normal drone, with any exhaust there is drone at 2k.. not sure if its 90 db though.. ill try measuring mine.

I8ABMR

The exhaust is great if you do highway driving. On the street in stop and go the drone can get annoying . I just keep it manual. Sounds great and the look on peoples faces when they hear the exhaust is priceless . Sounds like a racecar.