redidrum

Do you guys think that this Cat Bypass http://cgi.ebay.com/ebaymotors/Schne...temZ8029250266 will add much horsepower or are they a waste of time?

Any better deals out there or advice ? I know Vertex is a Rennlist sponsor.

Thanks,

Ron

stormmaster

I don't know how much horsepower they actually add.....but mine sure sounds a LOT better with one on it....that alone is worth the money....and yes it does breath better without the cat...

redidrum

Storm,

How difficult was the installation? Looks like muffler work has potential to break old bolts. Muffler shops usually cut everything off with cutting torch. What about the 02 Sensor?

Thanks, Ron

lostinatl

I noticed a slight difference. I did not seem to think there was that much difference in noise either. Maybe 1-3% difference on both power and loudness. I did mine myself the only bitch was getting the old bolts off and I had to cut the O2 sensor out...literally. Oh, and the Porsche dealer kept insisting that there was only two gaskets. I had to bring it in and show him.

stormmaster

To be honest....my brother did the install when he had it....I had driven it before the change....and right after....it is tuned with the O2 sensor unplugged....it runs better that way...

redidrum

I just remembered something about my car after hearing storm's reply. The P.O. had mentioned that he gutted the cat. Sounds like the same results. Could I be wrong?

ked

I think the most significant benefits of a cat bypass are to decrease heat & weight. Use new stainless n&b when installing, tighten again after a few days operation.

rnln

Well, think of it this way. Everyone wants a bigger diameter and less restrict muffler/exhaust. How much restriction of a muffler compare to the cat? Puting on a catless straight pipe is opened up completely free flow right there. All the gain should be on high end. Low end would lose.

redidrum

Thanks everyone ! Doesn't sound like something I really need to do at this time. I really want to install an entirely new exhaust with stanless steel headers and whatever works best for a muffler.

JCP911S

CAT alone really doesn't do much... i did it becasue a new CAT was $$$$

SSI/Headers and a free-flow exhaust are generally considered to be worth about 10-15hp you need SSIs if you want heat. Plenty of BS out there about exhaust sustems.... its a racket (pun intended) Check Steve Weiner's threads and follow his recommendation.

Crivens

will only help if you have your car live remapped.

www.red964.com/html/dyndex.php
www.projectsonly.co.uk

fixnprsh

it will help in mid-upper end, no need for re-mapping with an SC as it is CIS, just fatten the mixture a little, it will gain you probably 10hp max with a muffler also. Not bad for $135, Alot cheaper than SSI's if you're on a budget

They work really well on a 3.2 car, even better with a chip as SSI gains are fewer on a 3.2 as they need to push more air. I think 3.2's with stock heater boxes, premuff, and a good free flow muffler are pretty neck-neck with SSI's and you don't need to monkey around with heater pipes.

redidrum

Well, I went ahead and bought it. Good Price. My Cat is a rust bucket!!! What about those damn rusty bolts ? Spray with penetrating oil overnight or take it to muffler shop to have cut off ??? Most shops cutoff with cutting torch that I don't have access to. They may not do the job for legal reasons. They'll most likely break coming out. Will replace with stainless bolts.

Edgy01

You should also use ANTISEIZE on the nuts and bolts when you put it on.

One thing ALL Porsche drivers/owners should eventually own is a 4-1/2 in grinder that can take metal cut off wheels/discs. You could install that thing yourself with what you're going to pay that muffler shop to do it!

Dan

theiceman

Kind of funny really. My cat was removed and a bypass pipe welded in . Even all these years later looks like it was never there. It wasn't until I got on this list I realized the 78 even had a cat. !!!
Brings me to a question that I know someone can answer.
If you buy a " kit" that includes ssi heat excahngers and a muffler do they assume you have no cat or do you have to buy a bypass pipe to adapt. I have seen some kits advertised and although I don't have the $$$ right now I am just asking some prelim questions.
On a humouros side note when I was testing the waters last night with the finance dept ( wife ) she seamed dead set against it , when I inquired further she said why do I need a new exhaust system , she hasn't heard it run since I bought it :-) ......hmmmm .. good point ...