I just purchased a set of pre-owned Fabspeed MaxFlo mufflers for my 997S Cab. I'm really looking forward to the new sound, perhaps an added horsepower or two, and a little bit of weight loss in my rear end as well.
But I am concerned about the dreaded mid 2K rpm-range droning that seems to be present in this and many other after-market products of this type.
First off, would anyone be willing to comment on the relevance and scale of the droning thing? Is it likely to be worse/better/same on a cab? It is an overblown issues and specifically, how do Fabspeeds fair in the drone-wars?
Finally, I read somewhere that the root of the droning is the absence of the flexible coupler/adapters that are present on the stock mufflers. These prevent the mufflers from transmitting resonance to the rest of the car where, at certain frequencies, they doubtlessly create some harmonic amplification and thus the drone. This so? Would a trip to the welder to adapt a set of these flex couplers work?
Thanks,
Verde

 

no way, not from the flex coupler. The coupler mainly damps vibrations not the droning sound.

The droning is a result of resonance in the cabin. Better muffler designs eliminate those frequencies that cause this. I always had coupes so i dont know if a cab is less prone to this problem.

I have the FVD sound version mufflers which do not drone and keep the flat 6 wail i loved on my air cooled 911's.

 

Fabspeed's stuff is Drone-free. It's what I run on my own car and has been mainly the only exhaust out there I'll sell for the last 4+ years. I've ran just about every system on nearly every generation of 911, 964, 993, 996 and 997. For the water-cooled stuff, you'll be very pleased with their sound and performance.

 

There is less issue with droning in a cab vs coupe. I've had both, and ran the same mufflers on both. I'm no expert by any means but it seems that the larger the muffler can the quieter it will be in the cabin- Hence the bulky stock cans.

I do highly recommend getting a muffler that uses a flex section, otherwise you'll more than likely have vibration / buzzing of door or dash parts inside the cabin at certain rpm's. Each car is a bit different, some cars do this more than others.
You can buy flex sections from most muffler shops and have them put in on the inlet side of mufflers where they connect to the cats. Some cutting / welding will probably be required but is not a tough job for a muffler shop.

 

It's a tradeoff -- a little more power raises the potetial for drone. Even some exhausts which claim to be drone free can still sound boomy in the cabin .
An exhaust is a very personal thing to find that appealing sound combination with performance .

I like a little drone . What i don't like is drone with an exhaust note that I am not in love with . In fact -to me loving the note is more important than dreading the drone. Drone is a cars way of letting you know its either time to go faster or downshift and think it over .

 

Why not just do the "gundo" hack on your stock mufflers. No drone reported doing this mod. I am contemplating this mod too as an alternative to aftermarket systems with possible drone issues.


Jon

 

Thanks everyone for the quick responses.
I've been thinking about the gundo hack, but as Cattman reminded me, it's valuable (if only psychic value) to lose 20+ pounds in the rear end;
And I'm quite interested to know that the flex joint will not, per se, impact the droning. Even better to know that I'm not likely to run into the problem with the FS's. I'm not sure I'll have the patience to find the parts and a competent welder to minimize the wear and tear on the car from the added vibration.
I've been watching my tach during normal driving while considering this purchase and at the same time I thought a bit about some of the comments on the recent thread regarding rev'ing a boxer motor.
Overall, I'm not likely to run in to problems - because of the brand, the normal RPM range I drive in, and my realization that I've perhaps been babying my car for too long and this will be a great excuse to open her up a bit more often.
Thanks again. I think I'm going to enjoy this.
OTOH, I keep thinking I'm done with the mods. I've got a bunch of time on my hands lately and it keeps turning in to exploring new ways to enjoy my car. But at some non-trivial expense. THIS will be the last one. Honest.

 

Tried that with my 996- didn't care for the sound, but you can't beat it for the price. I agree it is all about trying different mufflers until you find the right "music" for your ears and driving comfort. I really like being able to hear some of the exhaust note in the car even with heavy traffic and the top down. The AH's on my 997 sing "drive me harder" in such a sweet tone, it's intoxicating. (plus I like that they are only 8lbs each pipe)

 

Verde I say got for it and slap them on! If you don't like em, get a different set and sell the curent ones. Most of us have gone throught quite a few brands before finding the personal fav.

 

Just to double-click on your post, you think the flex piece is a standard muffler part? That is, you'd suggest that I buy the right length/diameter and find someone to cut off the equivalent and weld in the new part (in to the new exhausts) before mounting the Fabspeed's?
I'm more likely to try it w/o and resort to this if it starts re-frothing my cappucinno? (Actually, I have a no food or drink rule in my P-car. I could save a whole 1/2 pound by getting rid of the cup holders. Hmmm, someone should do a poll about this).

 

Yep, the flex connector can be bought a pre-made part I believe. Throw on the FS pipes and see how it goes. PM me if you want to pick up the right size flex connector sections, I know a source.

 

Verde, Did you purchase these from Alan? I bought a set of wheels from him a few weeks ago. He is a good guy, and he does have a lot of stuff in his Garage. I went to his house, we put the wheels on his buddies 997 to check offset, then he let me take them to my tire shop to see if the wheels are true. Once it was OK, then I paid him.

If you didn't buy them from him, sorry for the hijack.

 

Thanks for the offer. I'll write up my impressions and take you up on it pending the driving results.