[Jack21]

Working on similar issue to make mufflers easier to swap with 3 bolt collecter flange rings.

Slip fit, as now using, tend to leak at first. When sealed with RTV copper they're difficult to separate.

Chirp test for Cobra mufflers. Drive into any enclosed parking garage.

1) With engine idling as you roll by parked cars, Cobra exhaust sets off virtually all car alarms. This is a Stage 1 exhaust. Too loud, and likely to cause permanent loss of hearing unless ear protetion is worn.

2) Blip the throttle as you roll by parked cars, exhaust then sets off virtually all car alarms nearby. Most of the rest of the car alarms located further away will chirp. This is a stage II exhaust. Too loud for street use, but may be OK for track use if helmet with hearing/ear protection is worn.

3) With engine idling as you roll by parked cars, some nearby car alarms will be set off. Most nearby car alarms will chirp. This is a stage III exhaust, and about as loud as you can stand it for street use.

4) Blip the throttle while rolling by parked cars. Some nearby cars will chirp, but none will set off. This is a stage IV exhaust and you can comfortably live with it on the street.

5) Rev the engine while rolling by parked cars. If one or two nearby cars chirp, this is a stage V exhaust. Pleasant for street use on a Cobra for top off, fair weather use.

6) Rev the engine while rolling by parked cars. No parked cars so much as chirp. This is a stage VI, or nearly stock exhaust. Car should not sound like riding inside bass drum with top on, and and sidewindows in for cold or inclement weather use.

Using 2 1/2" x 4" x 30" glasspacks (with the spiral scallops) and they're not bad sound level wise. About Stage IV on the Chirp Test. For top off use, they're fairly mellow for cruising. For top & sidewindows use, they have the "Riding inside a bass drum" effect.

Have 2 1/4" x 4" x 36" glasspacks and they're very mellow. About Stage VI on the chirp test. Minimal bass drum for buttoned up cruising. But the car is not as responsive to throttle input, so it takes a hit in the torque curve. Have pair of 2 1/2" x 4" x 36" that I'm about to substitute for the 2 1/4" and see if I can get around Phase V for winter driving.

And, Jones Exhaust has a "Stallion" muffler with a 4" case, 2" straight through core, 30" length, and "Car Chemistry" style perforated disk inserts around the core that is (according to Jones) quieter than glasspacks.

Keep you posted as I try different styles are tried.