The mufflers are riveted to the rest of the exhaust, which is stainless. The mufflers do have a different color than stainless. I've seen the same pic D-04 posted, which claims Ti is used. I'm pretty sure Mugen wouldn't lie about material use. Considering the Mugen is much lighter than the OEM exhaust, and I believe lighter than most dual exhausts, I'm betting the mufflers are Ti.

 

Regardless of what it's made out of, a friend's Mugen exhaust has NOT shown any evidence of turning blue. It's been on the car for a couple years, I think.

 

this is my experience also....

stainless doesn't turn blue....

 

But Ti will turn blue. Someone said that exhaust gas will never make it hot enough to torch it, but there are many places on my exhaust piping where it is now turning blue.

 

mugen exhaust from 00-04 has Titanium mufflers and tips with stainless steel piping.

Ti and stainless steel cannot attached together by welding. mugen uses rivets to attached them.

the mugen exhaust tip turns blue but not as much as the amuse exhaust.

 

I have the 04 Mugen exhaust and my tips were blue before I even mounted them (about .5 inches evenly around the edges). I assumed it was done by the factory for looks. I've had no other change to the color since.

 

1) Mugen wouldn't lie about its construction
2) Piping can turn blue, but once the gases have reached the muffler tip, I'm sure the gas has had a chance to cool down quite a bit.
3) Could the grade of titanium affect the amount it turns blue??

 

You're not the bearer of bad news because what you are showing in the picture is in fact titanium, not stainless. Only the piping and resonator are stainless on the Mugen, the mufflers/tips are titanium. My car looks about the same as the examples above with blueing only on the edges of the tips and all of the welds: