I bought two large-oval 60mm inlet I.D. mufflers from Simon to replace my carbon mufflers on my Akrapovic full system.
I wanted titanium mufflers back then, but they weren't available at the time.
Twins are hard on carbon mufflers due to the large pulses in the exhaust, and they all tend to get micro-cracks over time due to the pulses and heat degradation.
I bought two carbon rebuild kits while they were available, but knowing it would only happen again eventually, I decided to switch to titanium.
The LadyBird Performance (LBP) mufflers are very nice nicely made, seemingly lighter in weight than the carbon mufflers (haven't measured weight difference yet), and most important of all...durable.