My findings and experience with the purchase and installation of the RSR muffler system


Jim Calder

1996 Porsche 993 C4S (Wide Body)

59000 original miles


I am now the proud owner of the RSR muffler package that is now installed in my 1996 993 C4S. 


To my delight, I was able to order the muffler package over the Internet (via Robin @ the P-Car website) and was able to do so without any financial obligation.  The mufflers were sent to me freight paid and I was able to evaluate them prior to making any payment (including the shipping).  Needless to say, this was a ‘no-brainer’ in terms of ordering the system.


I was quite fortunate in that the Gillet style mufflers were readily available from Robin.  My wait period was only about 2 weeks.  Upon receiving the mufflers, I would have to say that everything was completely in check with respect to the RSR documentation on the website.  The modifications, original muffler integrity, and welding all appeared to be first rate.  As a general observation, it appears that Robin does very well in matching up the original mufflers.  As part of the deal, this is done on an exchange basis.  The muffler type, vintage, and approximate miles/usage are matched very well.  In a nutshell, not even an expert could tell any visual difference between the original mufflers and the ones provided under the RSR flag.  There is one exception worth mentioning and that is the RSR mufflers receive a great deal of attention in terms of cleanup.  The mufflers that I received had been swirl sanded/polished to a nice satin finish.  There is a picture on the website showing the cleaned and finished mufflers.  My mufflers looked exactly as shown on the website.  One last comment on the finish:  The cutting and re-weld was done at the rear seam of the muffler where the factory weld bead is located.  Upon reassembly, welding, and cleanup, there is virtually no evidence that the mufflers had seen some massaging.  These should pass for any show-car events where OEM requirements are in place.


As far as installation is concerned, it is as easy as it gets (at least for a muffler installation).  The factory flange fittings and bracketry make for a reasonably easy job.  One important note to make is the heat shield installation.  My shields (which are in great shape) were transferred from the old mufflers to the new when all mufflers were out of the vehicle.  This is quite simple with only 2 10mm bolts to contend with.  However, after a few miles of driving, I had rattles and vibrations with the shields.  I believe that this is due to the resonant frequency of the mufflers changing slightly (probably moves down a few Hz).  Not a real issue.  All that is needed is to put a slight twist in the shields prior to installation such that there is a slight residual stress.  There may be better ways to deal with this and it may not be an issue on everyone’s car.  My suggestion:  After installing the shields on the new mufflers, and prior to installation, knock on the side of the muffler casing with your hand like you were knocking on a door.  If you hear the shields rattle, eliminate it at that point (per the above suggestion) or by some other damping technique.  If the shields make no noise and the knock sounds like a thud….then you are good to go with nothing to worry about.  The shields are thin stamped aluminum and they do not take too much to make noisy or silent.


On with more important things:

The sound of the mufflers (with the stock tips) is just as Robin describes them.  (In my opinion) they make a Porsche sound how a Porsche should sound. The following is a brief summary:

1.      Sound at idle outside the vehicle – The sound is much throatier. On a relative scale, I would say that the decibel level increase is less than 4db at 1 meter.  This is purely a guess in that I do not have a sound meter.  One might say that it is ~ 15% louder?  In any event, it is a nice increase but is not loud or annoying.  It is a deeper more metallic sound.  I have used many mufflers for race and street.  My best analogy is that the sound is half way between the stock mufflers and a 3-chamber Flowmaster muffler.  Flowmasters are quite unique with a metallic-open sound and I think that the RSR muffler is very very close (but significantly quieter).  I also have a few friends that agree with the Flowmaster sound comparison.

2.      Sound at 3000 -6500 rpm outside the vehicle-My review here is not that accurate in that I have only heard one alternative driver in my car with me standing outside.  It definitely sounds beefy.  The sound is as referenced above.  I would equate the sound to be very close to a 3-chamber Flowmaster but not as raspy or loud at the extended RPMs. My guess is that the sound is up by about 6 db to 10 db at 1 meter for the lower and higher RPMs respectively.  The higher the rpm, the more aggressive the sound.  Most of my evaluation here is hearing the reflected sound off of buildings as I scream pass them.  I feel that the sound is very appropriate and pushes the db level only to a point.  I believe that it is quiet enough not to attract attention from ‘Johnny Law’ (knock on wood so far…).  When it does become loud enough to attract the “Law” you are already exceeding any posted speed limit within the US…so who cares…….)  RPMs in excess of 5000 rpm will notify anyone around that there is a Porsche in town.  There is no mistaking that the Porsche now sounds like a Porsche at RPM.  It sounds good and definitely turns heads.

3.      Sound at idle in the vehicle-Robin told me that there was a small increase in interior noise.  Frankly, I disagree.  My finding is that the interior sound at idle is nearly that of stock.  Bottom line…it is quiet with no noticeable resonance.  The valve train makes more interior noise at idle than the mufflers…what can I say.  I think that this is a very strong selling point here.  After all, who wants to sit at traffic lights (or take out a date) with a strong droning noise that gives you a headache.  If there is any increase in interior noise, I only detect it from the outside sound when the windows are down.

4.      Sound at 3000 -6500 rpm inside the vehicle-It is surprising that the sound pressure levels only increased slightly.  It is very reasonable.  Most of the increase in sound is from outside the vehicle.  From a resonance standpoint, I would say that it is very close to stock.  One might say that there is maybe a ~25% increase in noise at the higher RPMs.  The noise level is what I would consider acceptable.  A person can still communicate.  (Unlike with many performance muffler systems)


The only other notes that come to mind are related to performance.  As Robin claims, and is likely the case with nearly every other performance muffler, there is no significant gain in horsepower relative to the factory setup.  Anyone making such a claim for a stock motor is full of *#*#!  If the motor is modified with headwork, cams, and elimination of the catalytic converters, it is reasonable to conceive that horsepower gains are significant with a change of mufflers (but that is not the case here).  However, there is a performance increase.  After the installation, it was readily apparent that the motor is more reactive at the higher RPMs (4000-7000).  Possibly this is due to less stagnant regions of air within the muffler or better laminar flow???  That is my guess.  The bottom line is that the motor is much more responsive to throttle ‘blipping’ for down shifting.  It is as if about 4 pounds were removed from the 28-pound (or whatever weight it is) flywheel.  Prior to the RSR install, I found that I had to hang the throttle a bit longer for proper gear meshing.  Now, one quick stab of the throttle gets the job done.  (The day the motor is dropped I will definitely be replacing the “Anchor Flywheel” with a light performance version…I am used to flywheels less than 10 pounds in my SCCA racers)


Anyway, glad I made the purchase.  Thanks Robin


Jim Calder