Dave Middleton

I have recently bought a 993 Twin Turbo with the factory upgrade engine.
I am interested in debating the fitting of Fabspeed Muffler Bypass Tailpipes.
However, can anyone tell me if this will gain me anything, bearing in mind that I THINK the upgrade car had tweaks to it's exhaust.

OldGuy

Dave congrats on your purchase!!
I have a 97TT I put on Fabspeed bypass
pipes. What you'll get is a much better sound,
and you find the turbo lag is reduced becasue of the
easier breathing. I.E. it will spool up much better!!

adsc4s

Dave, I would say there will be no appreciable difference other than your ears fooling your brain because of the incredible sound. Although there is a small weight savings. If you want quicker spooling, get a LWF.

Anir

Dave,

Like OG, I believe the turbos spool up quicker. The weight savings is about 60 lbs - all from behind the rear axle. My car handles noticeably better without the mufflers.

Negatives: the sound is very nice, but might seem a bit loud after a few weeks, if your car is a daily driver like mine (maybe I should say if you're getting older like me).

ca993twin

The laws of physics would indicate that there should be a performance gain, both from the weight savings and the shortened and less restricted exhaust. Plus there is less heat being transferred to the turbos, which should also get a better cooling stream of air. I will confess that my numb butt was never really sure about the performance change.

I'm a REALLY old guy, and the muffler bypasses are only loud (to my ears) at cold start-up. After about a minute they quiet down. With the windows up, the sound in the cabin is hardly any different.

LT1

Get the bypasses they sound great! I cant wait for cold startup. Stock mufflers are WAY too quiet.

John H. in DC Area

Now I'm getting scared. My GHL's will be installed sometime in the next week or so (along with 100 cell hi-flow cats) and I'm looking forward to an aggressive, loud, but still pleasing sound. Anir, is it sheer volume that bothers you or is it tone as well? I suppose I'll save my Cargraphic mufflers rather than sell them just in case they need to go back on, though it would be a shame to add 60 lbs. back as well as a restriction for the exhaust discharge.

OldGuy

Addsion there is a noticable difference in time of spool
up. Before the bypasses the digital display would show
all digits as it spun up from .5 to .6 to .7 and .8. now
it goes directly from .5 to .8. so even the display is impressed!

Anir

John,

Don't listen to me! Due to the wreck last Labor Day, I was without the 993 for 6 months. During that time, I drove my wife's cushy Range Rover everyday, and it turned me into a woosy boy.

Seriously, the tone is great. It's just that I wouldn't mind a quieter car sometimes when it's been a long day and I want to listen to some (other) music on the way home.

I can promise you that the Fast by Ferraci pipes on my Duc were louder than the 993 without mufflers. Man, I miss that bike and that twin sound.

It's hard to justify rebolting a 60 lb pendulum to the back of our cars, isn't it?

viperbob

OK, so I resell Fabspeed so you can discount my thoughts. But I installed the Muffler bypasses on my car BEFORE I went into business and would not have chosen them to distribute unless I was satisfied with the product myself. The current models with a single mandrel bend pipe (no one else does this) that are equally as large as your cat pipes insure that they have the least back pressure. My new turbos will be here soon and I am planning to pump WELL over 600 HP out through them on my car....

Dave Middleton

Gents,
Thanks for your contributions. I am NEARLY convinced, but my one fundemental question remains.. As my car has the factory upgrade engine, is my exhaust not already a "sports" derivative? I do not know exactly what Porsche did to the exhausts of these cars.

dbf73

my current C2 has a primary muffler bypass - to me this is about the perfect sound level and tone. Can anyone compare this exhaust sound to the bypasses mentioned?

viperbob

Dave - As with most things Porsche does it is a compromise with a slant towards performance. The exhaust manifold is about as good as you can get for these cars (but they need work near the the exhuast flange on the inside weld) but the mufflers (sound reuqirements) and the cats (emissions and longevity) create a lot of back pressure and exhaust travel length after the turbos. Reducing either of these will help performance. So with the muffler bypasses, you are shortening the travel by several feet (about 40%), reducing back pressure, and then there is the 60 lbs weight saving. Not a bad deal...

Doug - The 993TT has only one muffler servicing each cylinder bank. SO if you do a muffler bypass, there are no mufflers left in the car..

Dave Middleton

Thank you, Bob for the help. I will now go for these bypasses (must get them in the UK from Design911.co.uk)

dbf73

Bob - I knew that but was trying to figure how the effect of cat + secondary muffler on the C2 compares to the muffling effect of cat + turbo on the tt.

I guess the real answer is to find a tt with the bypasses and listen.