cubby911T

Hello all....my '90 964 is setup with a rather custom exhaust from a 993. Pretty simple really - 993 heat exchangers + a modified cat which leads right into dual tailpipes (see pic).

About 20% of the time I LOVE this setup, but I have to be in the right mood to enjoy it. The other 80% of the time I find it annoying, especially early in the morning. Too loud and terrible resonance at 2700-3000 rpm. Many days that I'm on the fence about whether to drive the car to work I will choose not to because I don't want a headache by the time I get to the office. I hate that this is dictating how often i drive the car, because it is a joy to drive otherwise. It's actually slightly better since I installed cc:inserts into both tailpipes, but not enough to change my general feeling.

So....to my question. If I kept the 993 heat exchangers in place, could I use a cat bypass (or sport cat) and mufflers that are designed to fit a 993? Just want to be sure that 993-designed exhaust parts would mate up properly with my 964 before spending a bunch of money. In particular from my YouTube research, I really like the sound of Fabspeed Maxflo mufflers - any fit issues with these on my 964?

Any additional comments on Fabspeed or 964 exhaust in general would be welcomed too. Thanks in advance everyone!

Vandit

Here's a good illustration of the stock 964 exhaust system and the 993 exhaust system.
http://forums.pelicanparts.com/porsc...ml#post3841227

Does your car have the exhaust canisters in the rear quarter panels?

cubby911T

Vandit, not quite sure what you mean by "canisters". Are you referring to the twin mufflers from a factory 993 system? or to some remnant from the original 964 system? I can tell you that there are no mufflers of any kind installed right now and no remnants that i can see from the original 964 setup.

Steve Weiner-Rennsport Systems

That's precisely why its driving you nuts with the resonance and headaches,....

If you need a cat, your options are quite limited, however if thats not mandatory, one good option would be to do a little fabrication on the inlets and install an early 911 dual-in, single-out Sport muffler. Good performance and NO resonance.

My experience with the Fabspeed stuff is that they are all too loud.

fuch

Don't know if this helps....
993 engine
993 stock mufflers
De cat pipe
Sounds loud/gruff on outside but not so much on inside but more importantly no drone at all!!


Bumper brackets are tight but do fit,you just have to put a tab on the body bumper mount to move if forward a inch to clear the back of the muffler



Done...

Vandit

I'm referring to the two big muffler canisters that would reside behind the rear tires in each quarter panel on a 993. So your car basically has no mufflers. No wonder it is so loud.

I believe the 964 3.8RSR ran the 993 exhaust setup from the factory, and had the mufflers in place like the 993, but that car has the benefit of wide hips to fit those units. I don't know if you could pull that off on a narrow body car. (oops, just saw the post above me, looks like you can, but first put on your fabrication hat on!)

fuch

As Steve said above I had fabspeed supercups on as a stop gap and they were way loud and had that horrible resonance that's driving you nuts!!

You will fall in love again with your 964 when sorted...

cubby911T

Alright, this is very educational and informative - thank you! Fuch, you have demonstrated that with some fabrication, it would be possible to squeeze some 993 stock mufflers in there (looks great btw). I'd rather not have to get into fabricating, though - - what about aftermarket (ie: fabspeed maxflo or other) 993-style mufflers? I've seen pictures that show the aftermarket mufflers as being smaller than the stock 993 units. Do you guys think any of those would fit under my 964 quarter panels without need for special modifications? Even though they might be loud, they can't be louder than my current setup and if they solve the resonance issue I'd be delighted.

Steve, I could get away without a cat here in Indiana, at least for the time being. Ben McFarland (M&K) has told me in the past that he could probably engineer something like you described to fit my car. So that would be a viable option for me.

Steve Weiner-Rennsport Systems

If you do the M&K, ask Ben to make it quiet for you; most of the ones I've heard are far too loud inside the car for my ears.

The 993 muffler system (sans cat) like Fuchs did works very well if one adds a crossover between banks where the cats used to be. This retains/restores low & mid-range torque,...

fuch

I can measure my mufflers if you want & then you can ask your supplier to do the same & go from there?

Or try fdmotorsports.net as they have a very good rep on here & there your side of the pond....from experience it best to keep it as stock as poss for best results.. Fuch

fuch

Or as the far more knolagable Steve says...

Sorry I'm a bit slow on the keyboard!!

cubby911T

Cool, thanks guys. Steve, I will keep that in mind with Ben's product, although I put one of his mufflers on my old '89 Carrera and the volume was okay for me. Fuch, I just emailed Fabspeed directly to ask about the size of their version of Maxflo 993 mufflers and whether they would fit under my 964 without need for special modifications. I'll post the answer when I hear back from them in case anyone else might wonder about this in the future.

cubby911T

Just some followup after contacting Fabspeed directly about muffler fitment. Alex from Fabspeed was kind enough to answer my questions and informed me that the 993 maxflos should fit on my 964 along with their sport cat or cat bypass unit. It sounds like it should work, but I'd love to hear comments/advice from any 964 owners who have actually installed 993 style aftermarket mufflers. Not sure how many there are though in that category though.....anyway, thanks again to everyone who has commented on this thread.

Black930

Read the thread on my build I used fabspeed mufflers on mine and the fit fine in the rear quarter panel area. Slight modify of a bracket and you are good.

Earlydays

The increase in HP from the 1994 964 (247) to the 1995 993 (272) was basically due to the new exhaust system.......