Also, I have 2 Apex's as you can see. My wifes, when I plug the exhaust, it shuts right down. Mine decreases in idle for sure, but does not shuy down, and still sounds new. Should i replace the donuts, and with which ones. I'm a little nervous replacing with copper against the titanium, as it is brittle and more prone to crack vs the stock donuts??
slimjim: I have just replaced my stock donuts with 11,500kms on the sled. The sled was starting to sound slightly noisy in the tunnel like it had an exhaust leak. The donuts definitely were not junk, but they had started to de-laminate, and one clamp was spun around on the header so it must have been breaking down. I noticed the OEM donuts have what appears to be a metal mesh imbeded into them now, likely for additional strength and to keep them from disintegrating like the early versions did.
I also noted that there was a cross-hatch or knurled pattern from this mesh permanently embedded into the tapered mating surface of the titanium pipe, the header side was fine though as I believe these are stainless steel vs Ti.
The Titanium pipe flared end was still sound and without cracks, but appeared to be thinning out a bit from the embedding/squeezing of the mesh in the donuts. I figure the exhaust heat generated at this joint must make the surface of the Ti soft enough to allow this embedding of the mesh, as normally (cold) the Ti has a fairly hard surface.
After giving the flared ends a little buffing till smooth again, I opted to use the copper donuts, which appear to me to be slightly wider than OEMs, because the header clamps seemed to grip the joint much better and fastened up good and snug before bottoming on the spacer.
I've ran copper donuts on prior sleds and had no issues, however the pipes were stainless, not Ti. Will see how they hold up in the Titanium.
If you suspect your sled may have an issue, I would definitely have a look at the situation before too long.
