Greddy Exhaust Drone
 

sI recently installed my Greddy Evolution GT exhaust. It's a beautiful exhaust; nice welds/flanges/etc...

I love how it sounds on startup/acceleration/downshifts. My problem is that there is insane drone between somewhere around 2800-3200 rpm.

Does anyone else have this exhaust with this problem? I still have factory cats

A few things to note:

1) Everyone says the fitment on this exhaust is great, but that's not my
experience. The Y-pipe seems almost just a tad too wide. I had to loosen the cats to get it to bolt up (I tightened the cats back down). I'm fairly sure that the Y-pipe isn't upside down.

2) Even though they are centered vertically and horizontally, my tips seem to stick out more than other pics I've seen with this exhaust.

The exhaust doesn't make contact with any other parts of the car

Is this an install error on my part? Can it be related to my small problem with the Y-pipe? I'm out of the country at the moment and don't have pics, so I'll have to wait on that.

A bonus question:
This particular exhaust doesn't have any flex pipe. Given that I had to loosen/tighten the cats to get things situated, should I worry about things being too rigid?

Drone isnt a result of a fitment issue, it's the nature of the pipes. You could attempt to use GTMat and CCF (closed cell foam) and insulate the trunk area.

Or pick up a pair of these...https://uploads.tapatalk-cdn.com/201...af0b18ea22.jpg

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I'm just glad to hear it's not an install error. Also, my drone is probably too strong for something that just pulls 3.9 stars

You could try the eardrum delete mod. I've heard it solves the drone issue quite nicely!

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Oh crap, I just ordered this exhaust yesterday. Now I’m worried.

It should get here next week and I’ll definitely let you know if there’s drone.

:rofl2:

You have to remember that the catback has multiple sections to it. Adjustments will always be expected when changing out from OEM. This doesnt mean that the fitment is bad.


My Gemini doesnt really have drone with normal driving, but when Im on the Highway doing 70 < mph, theres drone. Its not too bad, I got used to it.

I wouldn't be concerned about the fitment except in every post I've read seems like people have really emphasized how well it bolts up. Glad that I'm not alone though

It looks beautiful and sounds beautiful. I am interested in how well your Y-pipe bolts up. Also, what year do you have? For the longest time, this exhaust was listed to be compatible with 09-14, then very recently the later model years were included. Probably nothing, but I'm still curious.

An exhaust will also change over time too.

I installed a ton of sound deadening in my hatch (for the subwoofer, not exhaust) and a side effect was my exhaust is MUCH more quiet inside the car now.

The only thing separating the driver from the exhaust tips is the plastic bumper cover, the carpet, and literally a panel of sheet metal. If you bang on it, it'll sound like banging on an empty 60 gallon drum. I put a few layers of butyl mat back there, and 80mil closed cell foam. Cut down on road noise some too.

I'd be interested in more info about that...

On the bright side... at least this will keep my wife from wanting to drive it.

I have a ‘17.

I’m also curious and crossing my fingers that I don’t have major issues. If it’s a little drone, I can live with that, otherwise, I’ll have the shop put in some resonators, if possible!

Ok, I have a '17 as well. Please don't forget to report back ok this. Other than the y-pipe fitment is great. The tips are very easy to center in the cutouts, but mine do stick out s little far

Quick synopsis: GTmat is less expensive Dynamat, no reduction in quality. These mats primarily reduce vibration coming through the metal body of the Z. CCF you can get on Amazon, it's just non-absorbent foam. Comes in rolls. This absorbs sound.

I did the entire trunk area, bottom and sides, shock towers, brace between the towers, and front/back of both rear wheel wells with GTmat and CCF. Two layers of CCF on the wheel wells. Put CCF all along the area behind the seats and under the OEM bar. Strategically placed GTmat and a full layer of CCF on the rear portion of the front fender liners and on the body of the car behind the front fenders.

CCF is what deadens sound so you want to absolutely go to town w that stuff.

I noticed a very significant reduction in road noise - can barely hear a pebble in the wheel wells. I'm quite pleased with the effort.

It's a PITA to do bc everything has to be cut to fit perfectly, no gaps. I highly, highly recommend you put the Z on jacks or a lift if you have one - spending 7-8 hours bending into the trunk space will cripple your back. Also helps to pull the seats out so you have room to work in there. Be gentle on the plastics and pull the FSM to see the pattern of removal.

Hope that helps.

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