rbeggs

My recently acquired '96 C4S came with Fabspeed mufflers. They sound great from the outside but inside, between roughly 2-3K rpm, there is an annoying resonant drone. Is this a characteristic of the 993 in general or of the 3rd party
pipes? Would reverting to a stock setup or RSR's make much difference?

Second question is: How advisable is it to re-chip the DME with these kinds of exhaust changes? My car has been chipped but nobody seems to know what or whose chip it is.

Your observations are appreciated.

R. Beggs

CarmG993

Not a characteristic of a 993 w/ stock setup or RSR's as far as I remember from my experiences.
I would be interested in other responses on remapping the chip after an exhaust is put on (~Steve what are your thoughts? )

Paulsha911

Based on first hand experience, I can tell you that I did not experience any "droning" with the following:
- OE Motor Sound Pkg mufflers
- GHL Loud
- and now DACH X-pipes + RSRs

Even with the x-pipes which make the RSRs fairly loud, I don't have any resonant droning in the cabin. OTOH, I noticed significant "droning noise" in the cabin for Fabspeed Supercups. Don't know about Fabspeed MaxFlo.

Regarding DME chipping, I have the Rennsport (Steve Weiner's) upgrade. No reporgramming was necessary changing to diff mufflers and even when I changed to the x-pipes. It did take a while for the DME to adjust the idling though, after I put the x-pipes on.

max911

My car with Fabspeed mufflers definitely resonated/droned at a certain 3-400 rpm range at around the 2600 mark IIRC. The worst of it is that the drone was there at typical highway speed in 6th, or freeway speed in 5th.
None of the above irritating sounds with stock mufflers or with the RRs currently on the car.
note: Motorsound Airbox cover installed when running the three above muffler types- although the drilled airbox cover only seems to alter the engine sound at high throttle angle (close to WFO).

I would put $$ down that your drone will go away with either Rs or the original mufflers.

max

Mark in Baltimore

What Max said. Unless you have RSR or OEM mufflers, expect a drone.

rbeggs

Not exactly unexpected info but very helpful in pushing me toward making a change.

Much appreciated. Thanks to all.

RB

Jim W

I had the same with BB mufflers PO put on car.
I replaced with OEM motorsound mufflers and drone is gone.

TheOtherEric

Fabspeed Supercups drone from 2400-2800 rpm. Dunno about Fabspeed Maxflos. RSR's do not drone (ok, I think maybe 1 person per 30 buyers might say they drone, but the vast majority of us say there's no resonance with RSR's).

TheOtherEric

p.s. if you have previous generation supercups, you may just need to renew the insulation on the removable baffles. Current gen supercups don't have removable baffles.

Mark in Baltimore

Fabspeeds drone; I've heard 'em on Sam N's car. Good sound, though.

TargaTango

In-car resonance can also be car dependent. In my previous 1996 Targa Tiptronic I had this issue in a major way with RSRs. I could not live with it. You can find my posts if you search my name. This is a different experience to most people with RSRs on this board but not all. I also had it to a much lesser degree with Rooks. I had no such issue whatsoever with the stock exhaust or with the Rufs, which I finally settled on. And, of all the mufflers I tried the Rufs were the loudest.