It is time to stop patching the exhaust and build a new system.
Looking for suggestions. I plan to construct and weld it myself with parts from summit racing. Need suggestions on
Muffler brand and size??
Do I need some backpressure built into the system??
tubing size?? headers are 2-1/2 inch at the colloctor.
Mark in FL

I did quite a bit of muffler and exhaust testing a few years ago. If you have a Bursch header ( 4 into 2 into 1) it is good for torque. The others make more top end power and feature a 4 into 1 style collector. The pipe size should be either 2.5" for torque or a pretty much stock engine. Use 3" pipe if you feel you need to fill in the top end power. For mufflers I tested 6 different mufflers and found some interesting details.
1. use a straight through design. ( no Turbo mufflers) It should have a perforated core.
2. Best overall performance was with a small ( 16") resonator located where the Cat would go.
3. Best performing mufflers: Borla XR1, Magnaflow, Dynomax ( round style)

All of these did a good job of noise attenuation and power was very close, with the edge going to the Borla. Greg F

Thanks for the help. Do I need any small flex joint to help with vibration???

There is no need for a flex joint if you use the factory Porsche hangers. Stay away from the cheap ones you can get from NAPA, etc. you will have constant problems.

I agree about using ALL of the stock hangers will keep problems to a minimum. We don't use the traditional 2 or 3 bolt flanges and gaskets here. We swap those for a gasketless "Buick Ball" arrangement that never leaks and requires no gaskets. It allows some movement if the car goes offroad or into the gravel as well wiuthout breaking anything. Greg F

I looked all over Summitt racing catalog and even googled Buick ball flanges and could not find a reference, and I have no idea what they look like. Could you lead me in a direction or have a picure of a buik ball flange.

Mantissport solution to your problem is use a slip joint between the headers and exhaust pipe running to the back. Any muffler shop can do this. This reduces the stress to the headers, cracking at the header flanges. Also your can remove the head without removing the headers, or going underneath to undo the headers from the exhaust pipe. Just rotate header off the head.

Greg:

Is this the joint type?

You guys do not like the V-Band Clamps?

1. Slip joints can allow the exhaust to pull out and eject.
2. V band clamps are great, but expensive and tend to not allow the joint to move enough.
3. Yes, those are buick balls. Easy to assemble, zero leakage, will not pull off if you go offroading or run over debris, and zero wear or maintenance required.

Greg F