All right, 2 years ago when I was still ignorant enough to a rotary, I took my cats off and put the racing beat replacement pipe in place of them. Still having the stock muffler, it sounded horribly tinny and crappy. Not having enough extra cash for a RB muffler, I went in and had the local exhaust shop splice in a good size glass pack into the test pipe to temporarily calm it down, which worked well. I now just recently put on the RB header, and will save up for for the muffler soon. However, I'm assuming, even though only driven in the summer, the glass pack is nearing the end of its life. My question is-
Will I be losing power or backpressure by leaving the glasspack on there, even if most or all of the insides are burnt up? It is obviously larger than the pipe in diameter-

 

Usually with glass packs, they burn up and eventually blow out. If they don't blow out, what you'll notice is it'll slowly get louder, and start droning like crazy.

I've never heard one on a Rotary, but a worn out Supertrapp can make a 4-cylinder deafening, so I can't imagine what it will do when the core is completely gone...

 

The packing of the glasspack will burn out, but the perforated steel pipe inside will remain intact.

 

I had my car with the glass packs on it for a year before I sold it.. never had a problem. Install them backwards, they last longer.

 

I have had the same glass packs on my car. They are located back by the stock muffler. It has sounded ok and they have now lasted 2.5 years. No signe of blowing out. I have just recently blown a flange gasket at the exhaust manifold dump. That has made it loud.

 

Good. Question answered-Thanks!