tas02

iTrader: (2)

Originally posted by macah:

"IMO the drone is minimal. It's bearable. ..."

I convinced myself of this as well. I definitely didn't spend 4k upgrading from standard to long tube unequal length headers just to get the car to sound better. It was an 11 sec. et I was after. The melodious sound a pleasant side effect.

And the Bazooka pipes will not reduce drone.

FFM

Drone is caused by vibration. You either need to dampen the piping or you need to remove the frequency causing said vibration. Helmholtz chambers is what is generally used to remove this. I would imagine a strong majority of these exhausts were developed with the factory headers, thus why they seem to drone once replaced with aftermarket units.

Best best will be to have helmholtz's chambers installed.

BLKLBL

Does anyone have a cutaway picture of the Borla mufflers?

I orderd some silencers to fit in two of the four exhaust outlets in the Borla mufflers.. I'm hoping blocking off 2 out of 4 will kill the loud bass tone and drone from this system.

The ISF is my daily driver, and the Borla w/stock manifolds is a little too loud for my neighbours at 5am

LexusNN

iTrader: (5)

In one of the muffler delete threads, somebody took the small rubber weight off of the stock muffler and strapped it to the straight pipe. This supposedly absorbed the vibration and eliminated drone.

FFM

They are common on a lot of OE exhausts. You could find one at a junk yard and have it welded to the mid pipe.

MileHIFcar

This statement sounds spot on! It would make sense as the drone wasn't nearly as bad with the stock restrictive manifolds compared to PPE headers, it changed the whole tone/frequency of the drone and amplified it

I would love to see some Helmholtz chambers welded onto the Borla to see where they do it and see clearances?

mahcah

iTrader: (3)

I think I might try this as well.

MileHIFcar

Curious, let me know if and when you do this and the results!

mahcah

iTrader: (3)

10-4. Going to hack an IS250 exhaust and use the rubber on the Borla setup.

MileHIFcar

I have my stock exhaust still, so I'm curious what part they're talking about and where they hooked it up?

mahcah

iTrader: (3)

Id probably hook it up around the resonator or muffler section. That's where the sound is coming more out from. My hypothesis. No scientist here.

LexusNN

iTrader: (5)

On the ISF stock exhaust, it is bolted on near the driver side muffler. They then clamped it on the new pipe and the drone was gone.

mahcah

iTrader: (3)

Makes sense. The piping on the driver side is longer so it would have more resonance. Kinda like a ruler when you pull on it at the edge of a desk. The more hanging over the edge, the more resonance and vice versa. I don't think I'm explaining myself clearly but this is something i used to do in grade school lol.

MileHIFcar

Well if this works, then talk about a cheap way to fix the drone

j3ff

How interesting. I've always wondered what that rubber was for; I thought I read it was a bump Stop but this makes more sense.

I would say "drone" is subjective. Everyone is going to have an opinion on what's tolerable. My hks ssm has helmholtz resonators and all I can say is that at 2K rpm, it's quieter than the stock exhaust. 2k seems to be the most pronounced spot for drone with all exhausts with the isf.