Exhaust Improvements, or lack of it for 996

Has anyone run there 996 with just the cats and a straight pipe, no exhaust? I just came back from the shop doing the work to my 996. He pulled the mufflers for me. The car sounds wicked loud.

Though I wouldn't mind just using straight pipes in place of the mufflers it'll be to far noisy unless I'm at the track but normal daily drving i'll be pissing off the neighborhood. If you're looking into exhausts give fabspeed a try-not too loud but loud enough. Regards. mike

I've used fabspeeds on my 90C2 Cab; 94 Speedster; 98 993CS and now on my 2002 996 C4 Cab. They are the greatest...burble at idle, nice throaty sound at 2000 and great rrrrraaaaapppp at around 4500. Don

the fabspeeds may sound nice but the 90 degree pipe off the cat sounds good. With a wire mesh resonator it isnt too lod. My mechanic had a 993 Turbo with the cat/straight pipe combo which was louder...kind of pipey, hurt your ears but mine didnt sound like that....the straight pipe is deeper, not pipey. I am going to play around a bit with it. But it seems that if you add any "exhaust chamber" you remove the rawness from the sound... so far i just heard the car with the cats, WITHOUT the 90 deg straight pipe..so i think that may soften it a touch.

You cannot compare the Turbo with a NA engine. While straight pipes will work on the Turbo, a NA engine requires backpressure and will loose some HP without mufflers. You should drive your car without mufflers and see what it's like.

Aren't you concerned about eardrum popping resonance at casual freeway cruising with "straight pipes "? Just blipping the throttle in the shop is no way to judge a muffler system ( or lack of) .

I second Tobias' comments---the car will have less bottom-end torque. The car might sound fast, but there will be a power decrease. It'll be a difference you will feel seat of the pants. Look forward to your impressions of this mod if you go for it. Good luck!

Ok, I am interested in hearing your reasoning ro theory on the less restrictive exhaust. Mine is this. The reason a free flowing exhaust generates more hp in a vehicle is b/c there is nothing constricting the "blowing" effect of the motor. That is all motors suck and blow. They suck in gas and blow out exhaust. If a motor is ineffcient in either sucking in gas or blowing out the exhaust that will reduce the hp the motor can make. If a motor cannot expell all of its exhaust on the second upstroke of the piston, when the second downstroke occurs, with exhaust still in the cylinder the burn of the fuel in the upstroke wont be as efficient. What effects the ability of a moter to expel exhaust?. The muffler and headers. The stock headers on the 996 are unequal lengths...that is the exhaust tube for cylinder 6 is shorter than cylinder one's....most aftermarket headers have equal length tubes. That is why they generate more hp b/c there is more volume in the tubes to expel the exhaust in ALL of the cylinders. Does this make sense? What is your paradigm on back pressure?

Most high-end cars have well engineered engines with better than adequate breathing. If you alter the exhaust characteristics, you must also modify the intake. Leaving everything else alone and increasing exhaust flow will hurt performance more than help it.

Hi Viken, thanks for responding. I don't follow your logic though... you wrote.. "Leaving everything else alone and increasing exhaust flow will hurt performance more than help it." If that was the case, why would the GT3 cats that I have on my car give me a noticeable improvement in. I did nothing else to my car and there is a noticeable difference in how the car responds to throttle, that even other 996 drivers notice when they drive my car?

What I think Viken is stating is that power gains are synergistic when one improves the intake & exhaust efficiency of any engine concurrently. As has been published by numerous independent authors, famous engine builders and can be readily seen on chassis dynos and etc--- adding a well designed hiflow- reduced backpressure exhaust system -- will add horsepower and sportscar sound to each and every single Porsche streetcar ever made in history. Even the 959 ran much better without the "optional" catalytic converters. Every Porsche streetcar can have added power by simply adding a quality freeflow exhaust system. The power gains are synergistic and magnified by making intake flow improvements while youre making exhaust backpressure reductions. The magic is to then TUNE the car for the right fuel and ignition curves. Porsche, Ferrari, BMW, and other manufacturers operate end engineer under specific criteria and negative variables that tuners and car owners dont have to adhere too. Thats the beauty of the aftermarket and pleasing any car owners in terms of their own objectives. Fabspeed Motorsport exhaust systems will add power on each and every Porsche or we will not sell it. They always have and always will 100% guaranteed! 996TT-GT2 system was tested in GERMANY on the engine stand at RS TUNING recently and made significant power over anything else available in "der fatherland". webpage for the Porcshe performance

Hi Joe of Fabspeed. Love your products-exhaust and cold air intake. Have You had a chance to provide the dyno numbers on the cold air intake? I know you stated figures from people of the forum but have you done any numbers yourself. Its a great selling point when you can dyno numbers yourself. Regards. Mike

If someone in the Philadelphia area want to come out for a DYNO test I am all for it. I have had many dyno results for Fabspeed products in terms of the headers, Maxflo mufflers, Chips FVD & Piggyback, and BMC F1 airfilter. I dont have any stand alone test figures as of yet on the Fabspeed COLD-AIR 996 hiperformance airintake kit "alone" as of todays date. I have several reputable shops that did everything all at once like the Rcaers Group and S Car GO Racing. They all found over 25HP on a 996 with a "chip" as the final tuning. The Rcaers Group [phone removed] found powre to be increased in the 30+ range. As soon as I have data you can bet I'll post it. In the meantime the stop watch doesnt lie WITH quicker acceleration times from 3000-6000RPM acceleration sweeps. Any 996 owner can without a doubt feel the power in the seat of your pants guaranteed! So rest assured its one the best performance values and improvemnets anyone can make to a 996 for $225 and a BMC F1 airfilter. You dont need dyno tests to notice the power and sportscar sound improvement.....its obviuos the 996 picked up power and sportscar sound with our Fabspeed Cold Air kit as well as with our other proven bolt-on performance parts! Its also obvious and you dont need a physics PHD...... and grown intelligent people dont have to be told its cold outside when its 10degrees fahrenheit or that strong SUN UV rays can burn your skin after prolonged exposure. If anyone wants to do a dyno test call me at Fabspeed Motorsport 2156464945 In the meantime have a great weekend and enjoy your Porsches one and all! Performance for the Next Millenium

I can vouch for the Fabspeed airbox, BMC F1 and muffler system making a significant difference in 'bum in seat' testing, and DEFINITELY sounds much more impressive than stock. The induction sound improvements are really cool, plus you'll get a noticable upgrade over 4/5000 rpm through to red line, in my case with a remapped tip. Headers? I did the upgrade, but my dyno results suggest that I might of actually lost a little bit of torque at the expense of top end improvement. However, I wouldn't have known if it wasn't on paper so I guess I don't miss it. Graham

I'm curious. Is the BMC F1 any different than the K&N in terms of airflow?