Header options advice needed

[edc]

Originally Posted by NewArt

The only 200 cell secondarycats that I see on e-bay are the Circuit Werks brand at around $400 or so. Are you referring to these?

Circuit Werks isn't a known name here so it's not these. Search eBay UK for a comparison. There are a couple of retailers here that sell the mid/secondary pipe with cat. My old ones with 100 cell cats eventually failed the emissions so I have reverted back to the standard ones until I get a new car core welded back in.

If the straight mid pipes are cheap enough there's no reason why you couldn't modify those to insert a cat and copy the shape of the ones with the cat already in.

[j.fro]

The exhaust is one of the places the Porsche used to keep the 986S down on power and out of the 996 market share. If you compare the two cars' exhausts and consider how much more power the 3.4 makes over the 3.2 it starts to become obvious. Anyhow, better headers are step 1. I've had the Chinese headers on my car for over 10 years now and they worked great. Were I to do it again, I'd go with the larger tube 987 Chinese headers which are only slight more $$. I've got the Fabspeed secondary pipes with 100 cell cats welded in. The advantage over stock is the larger diameter along with the much less restrictive cats. Originally I had the pipes without cats coupled to a Borla muffler. The SCCA judges started hassling me about the car being over their dB level so that's why I added the cats. After a few years the Borla fell apart so I had single chamber 2.5" Flowmaster mufflers welded in place, maintaining the 2.5" diameter throughout the system. Sound is good, power is 244 at the rear wheels.
From what I understand, the stock muffler actually flows pretty well despite the small pipe diameter. As well,it's got the acoustic tuning to eliminate drone. Probably the biggest advantage to dumping the stock muffler is the weight loss.
Hope this gives you some ideas to consider.

[10/10ths]

...the critical part of exhaust flow is immediately upon exiting the exhaust valve. Long tube headers with no cats allows the exhaust to QUICKLY get outta the combustion chamber and if tuned properly helps “scavenging” that allows intake flow to be better in addition to exhaust flow.

The exhaust gas cools very quickly and slows down as it cools due to the laws of thermodynamics. This is why cats that are further downstream don’t have as big a detrimental affect on exhaust flow.

The stock muffler actually works really well and the car NEEDS either the original muffler or a high quality copy of similar shape and mass because the entire drivetrain WITH the muffler was balanced and tuned by Porsche to act as a mass balancer of sorts for the entire vehicle. Only a big single can will prevent the horrible drone on the highway in top gear.

The FVD Brombacher “Sound Version” muffler is very expensive, but it is built out of T316 stainless, a much higher quality of steel then even the OEM muffler, provides a great sound, will stay shiny for life, and will never burn out. That is the best option for a real world, street driven car.

If you don’t care about cross-country driving without a headache, then buy any muffler you want.

The high flow cats in a quality secondary pipe won’t affect your power output much. For a street car, you really should run them if you use long tube, catless, headers.

The factory header with the cat built in is that close to the engine for a reason. The factory needs the catalyst to get “lit off” as fast as possible to pass the government smog tests. The cats need heat to work, and sticking them in the pipe as close to the engine as possible let’s them pass the smog test, because that factory test has a cold start portion and the cats have to get hot as fast as possible to pass.

For us out in the real world, where we drive to a smog check station, having the cats eliminated from the headers and just mounted in the mid pipe downstream doesn’t hurt us, because the car is warm and the cats are hot by the time we get to a smog check station and they can scrub the exhaust clean.

It’s just science.

[Cunningr]

Originally Posted by 10/10ths

...the critical part of exhaust flow is immediately upon exiting the exhaust valve. Long tube headers with no cats allows the exhaust to QUICKLY get outta the combustion chamber and if tuned properly helps “scavenging” that allows intake flow to be better in addition to exhaust flow.

The exhaust gas cools very quickly and slows down as it cools due to the laws of thermodynamics. This is why cats that are further downstream don’t have as big a detrimental affect on exhaust flow.

The stock muffler actually works really well and the car NEEDS either the original muffler or a high quality copy of similar shape and mass because the entire drivetrain WITH the muffler was balanced and tuned by Porsche to act as a mass balancer of sorts for the entire vehicle. Only a big single can will prevent the horrible drone on the highway in top gear.

The FVD Brombacher “Sound Version” muffler is very expensive, but it is built out of T316 stainless, a much higher quality of steel then even the OEM muffler, provides a great sound, will stay shiny for life, and will never burn out. That is the best option for a real world, street driven car.

If you don’t care about cross-country driving without a headache, then buy any muffler you want.

The high flow cats in a quality secondary pipe won’t affect your power output much. For a street car, you really should run them if you use long tube, catless, headers.

The factory header with the cat built in is that close to the engine for a reason. The factory needs the catalyst to get “lit off” as fast as possible to pass the government smog tests. The cats need heat to work, and sticking them in the pipe as close to the engine as possible let’s them pass the smog test, because that factory test has a cold start portion and the cats have to get hot as fast as possible to pass.

For us out in the real world, where we drive to a smog check station, having the cats eliminated from the headers and just mounted in the mid pipe downstream doesn’t hurt us, because the car is warm and the cats are hot by the time we get to a smog check station and they can scrub the exhaust clean.

It’s just science.

Thanks for the run down, already kinda had an idea on the long tubes after thinking over it. But learned something new on the cat placement and why.

[The Radium King]

Originally Posted by j.fro

The exhaust is one of the places the Porsche used to keep the 986S down on power and out of the 996 market share. If you compare the two cars' exhausts and consider how much more power the 3.4 makes over the 3.2 it starts to become obvious. Anyhow, better headers are step 1. I've had the Chinese headers on my car for over 10 years now and they worked great. Were I to do it again, I'd go with the larger tube 987 Chinese headers which are only slight more $$. I've got the Fabspeed secondary pipes with 100 cell cats welded in. The advantage over stock is the larger diameter along with the much less restrictive cats. Originally I had the pipes without cats coupled to a Borla muffler. The SCCA judges started hassling me about the car being over their dB level so that's why I added the cats. After a few years the Borla fell apart so I had single chamber 2.5" Flowmaster mufflers welded in place, maintaining the 2.5" diameter throughout the system. Sound is good, power is 244 at the rear wheels.
From what I understand, the stock muffler actually flows pretty well despite the small pipe diameter. As well,it's got the acoustic tuning to eliminate drone. Probably the biggest advantage to dumping the stock muffler is the weight loss.
Hope this gives you some ideas to consider.

and consider the 987 oem muffler with cats built-in as well (if you want to keep cats at all).

[BYprodriver]

Originally Posted by The Radium King

and consider the 987 oem muffler with cats built-in as well (if you want to keep cats at all).

I have a used set of Fabspeed primary sport cat manifolds I'm going to sell if anybody wants to go that route.

[Cunningr]

Originally Posted by edc

Circuit Werks isn't a known name here so it's not these. Search eBay UK for a comparison. There are a couple of retailers here that sell the mid/secondary pipe with cat. My old ones with 100 cell cats eventually failed the emissions so I have reverted back to the standard ones until I get a new car core welded back in.

If the straight mid pipes are cheap enough there's no reason why you couldn't modify those to insert a cat and copy the shape of the ones with the cat already in.

The circuit werks are made by a company in Texas, I just received my secondary cat delete pipes from them. Visual they look well built, price was right, and they shipped within 2 hours of me ordering them. Not sure when they will get installed to do review, probably fall. I want to get an fvd sound version put in same time, plenum throttle, and the fvd tune. So spreading the purchases out several months.

Anyway the user reviews i have read on the circuit werks have been positive, so hope they work well.