Cat bypass with resonator

[Dave80GTSi]

Originally Posted by Dave80GTSi

I have a set of these Circuit Werks secondary resonator pipes on order and incoming to me, arriving probably early next week.

I can take some pictures and post here then, if you wish.

Thanks - DM

Picture looking up the exhaust end of the resonator. As you can see, it is a straight thru design with no obstructions.

[Cunningr]

Looks nice, only thing I can think is they suppose to look like a cat installed in case of a visual inspection.

[edc]

Originally Posted by Dave80GTSi

Picture looking up the exhaust end of the resonator. As you can see, it is a straight thru design with no obstructions.

Is there a reason you stuck with the standard manifolds? You can get a freer revving engine and a shade more power with some cheap but better flowing ones.

[Dave80GTSi]

Originally Posted by edc

Is there a reason you stuck with the standard manifolds? You can get a freer revving engine and a shade more power with some cheap but better flowing ones.

That’s a fair question.

I considered the use of aftermarket headers, but I selected the non-cat OEM manifolds out of my interest in keeping the system as laterally compact as possible, avoiding the “splaying out” of the header tubes beyond the valve covers.

The OEM non-cat manifolds might not flow as well as would a set of proper headers, noted. But for a street car I figure that they will serve me well enough, and they are most certainly a big forward improvement over the OEM cat versions which are a flow horrorshow.

Plus, you then know right from the start that the OEM parts will fit properly, without the need to monkey around with the often times imperfect configurations and alignment problems that one can many times see with aftermarket exhaust components. ( ... but having said that, the Circuit Werks resonator pipes, not shown in these new pictures below, turned out to be a perfect fit!)

Thanks - DM

[edc]

If it helps my car is only road use and I've fitted the cheapy aftermarket manifolds to both my Boxsters with no issues and a slight improvement both times. I saw your pics and saw that you had already removed them. That is the one part that nornally deters people. The lbojr cost to remove them is often more than the manifolds themself.

[Dave80GTSi]

Originally Posted by edc

If it helps my car is only road use and I've fitted the cheapy aftermarket manifolds to both my Boxsters with no issues and a slight improvement both times. I saw your pics and saw that you had already removed them. That is the one part that normally deters people. The labor cost to remove them is often more than the manifolds themselves.

I assume that the comment above refers to the often encountered difficulty in getting the 6 steel manifold bolts out of the aluminum cylinder heads without snapping them off?

If so, having the bolts out thus offers the perfect occasion to replace the lot of them with M8 x 42 mm long studs and matching SS flanged nuts

Years from now, whoever might have any need to remove these manifolds will thank you for your efforts to "stud" them today!

Cheers - DM

[gsy4771]

Do you still like the setup? I'm thinking about the circuit werks pipes you installed and wondered how they worked for you?

[ike84]

Originally Posted by gsy4771

Do you still like the setup? I'm thinking about the circuit werks pipes you installed and wondered how they worked for you?

Just so you know, those"resonators" are just glass packs. I've not heard them in person but if you're keeping your stock muffler I'd be shocked if they did anything at all in terms of sound.

Sent from my SM-G970U1 using Tapatalk

[Dave80GTSi]

Originally Posted by gsy4771

Do you still like the setup? I'm thinking about the circuit werks pipes you installed and wondered how they worked for you?

I'll assume that this is directed to me, since I posted the pictures?

If so, then yes, I've been very pleased with the stock non-cat manifolds and the Circuit Werks "resonators". Aside from the fact that all of the white insulation which was a part of the "resonator" portion of the Circuit Werks pipes was blown out after about the first 10 minutes of use, ending up in the muffler!

Fortunately I was able to fish out most of this insulation after removing the muffler - what I could not remove eventually blew out of the muffler's tips.

One difference between the older pictures that I posted and the car as it sits today is that I ceramic coated the manifolds, as you can see below:



The use of the non-cat OEM manifolds resulted in a notable performance boost as compared to the cat manifolds as shown in the second picture in Post no. 23, so I am well pleased.

DM

[gsy4771]

Originally Posted by Dave80GTSi

I'll assume that this is directed to me, since I posted the pictures?

If so, then yes, I've been very pleased with the stock non-cat manifolds and the Circuit Werks "resonators". Aside from the fact that all of the white insulation which was a part of the "resonator" portion of the Circuit Werks pipes was blown out after about the first 10 minutes of use, ending up in the muffler!

Fortunately I was able to fish out most of this insulation after removing the muffler - what I could not remove eventually blew out of the muffler's tips.

One difference between the older pictures that I posted and the car as it sits today is that I ceramic coated the manifolds, as you can see below:



The use of the non-cat OEM manifolds resulted in a notable performance boost as compared to the cat manifolds as shown in the second picture in Post no. 23, so I am well pleased.

DM

Thank you for the response. How you had issues with the car passing inspection? You do not have any cats with your setup? Also any warning lights?

[jbreak]

Originally Posted by gsy4771

Do you still like the setup? I'm thinking about the circuit werks pipes you installed and wondered how they worked for you?

I have the circuit werks resonated test pipes as well on my '99 and love them except the occasional catless smell when stationary w/ the windows down. I've had them on for about 2 months with the O2 sensors hooked up to them and still no CEL. Also running Soul Performance's valved muffler bypass w/ oem muffler so she can get rowdy with the press of a button!

[flmont]

ECU Doctors website show's 499.00 for a upgrade,..but my 2002' ( I forgot ) has 4 02 sensors 2 B4 the cat and 2 After..is there still a chance I could do the 99' header system on my 02' with a plug in test only,but with only two o2 sensor's ? Thanks Frank

[edc]

I know most of the users here are in the US but what you post above as the non cat manifolds are just the standard ones in Europe. For 986 we have the cats in what you guys cal the midpipes. With the 'sports' manifolds there is a noticeable freeing up at the top of the rev range and the engine much more willing to rev more with more urgency.

[edc]

I have the right fitting of these
uk/itm/PROFUSION-LAMBDA-SENSOR-SPACER-FOOLER-ASTRA-GSI-VXR-2-0L-TURBO-CORSA-VXR-/264359609740?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0

[edc]

My car is an actual ROW car and I have written exactly what has happened to my car.