Dear all,

My C4 is fitted with a TechArt bypass tube which runs parallel to the bumper. Which part of the exhaust does it replace ? I've never driven a 964 without it but I don't think it produces much more than extra noise...

Thanks in avance.

 

What you have is called cup pipe, a common upgrade. It replaces the 1st muffler, also saves a lot of weight. If you want to go back, you can find that piece on ebay in Europe or US for 25 to 50 dollars.

 

To be more specific, what you have is a Primary Bypass, often referred to as a "Cup Pipe". It is probably the single most popular "upgrade" for a 964.

 

Hey Folks,

Couple of questions on this one;

1. How much more noise can you expect ? I have the air box drilled and love the fact that the car only roars under load - will the cup by pass make it a noisy car period ?

2. Is there any performance gain without chipping the car ? or even worse is there any performance hit if you don't chip the car at the same time.... I read about back pressure being good for NA cars (if you want to explain the science her too then please do :-)

Thanks,
Andy

 

Andy, with the "Cup" bypass and a drilled airbox...I would take a risk at saying YES, there is a performance gain. What is under fire here it how much performance gain??

The bypass and airbox mod will provide a gain with or without a chip...I think it's the chip that provides maximum controversy. I have not been convinced as of yet to use anybody's chip.

***But I'm game...anybody willing to send me one??***

 

Hi NY Andy to aswer your questions!

1. How much more noise can you expect ? I have the air box drilled and love the fact that the car only roars under load - will the cup by pass make it a noisy car period ?

The sound of the cup pipe is louder but sportier than the standard exhaust. When you fire up the engine ist great, but after a long journey I must admitt that its getting on my nerves. I have a friend who has another much smaller bypass than the cup pipe! In French we call it "Coude", in German "Rohrbogen" (this will maybe help you to find the picture on the website of FVD or Cargraphic. The sound of this smaller bypass is deeper than the one of the cup pipe. In my opinion it sounds better and it's cheaper (150 Euros) than the cup pipe (200 Euros)

2. Is there any performance gain without chipping the car ?

I agree with Jeff and say Yes! You will certainly gain a bit HPs but not to enough to let you think you have a new engine with much more HP's

Just to give you a bit more infos, my car (1991 C2) has the Chip, the cup pipe and the KN intake filter. The three things together are said (I don't believe it though) to bring you between 10 to 25 HPs more Since I do have the three things I can assure you that the before/after difference is not really noticeable.
My advise to you would be to change your muffler (do you cakla the like that?) for the "Rohrbogen"! By doing this you will get a much more sportier sound on acceleration. And that is very much of a satisfaction. If you want to keep within Porsches developpments Than you have to opt for the cup Pipe, which was a standard fit to the real cup cars.
Enough <img src="graemlins/a_smil17.gif" border="0" alt="[blabla]" /> now
Hope this helped you a bit a greetings to the U.S.

Thomas <img src="graemlins/xyxwave.gif" border="0" alt="[bigbye]" />

 

You might read the thread entitled "Performance Enhancements Study II." Careful before and after dyno testing showed this sort of a modification was measured as a gain at the wheels of 3.2 HP and 4.1 ft-lbs of torque. At least on my car FWIW.