Ceramic on pipes does 3 things: increases corrosion resistance, reduces ambient temperature by trapping more heat inside the exhaust (cooler to the touch) and the most important performance benefit, increases the exhaust gas scavenging.
The last piece is the most important if your goal is some performance benefit. Because exhausted gas is "puffed" by each cylinder into the pipe, it is rather turbulent air, and has a narrow band of heat, with much cooler air on the outside edges of it. Ceramic coating helps raise the temperature of more of the gas so it actually vacates the pipe quicker and more completely with each "puff". Hotter air travels faster than cooler air. Same principle as a river. Faster current is in the middle of the river, eddy currents occur on the edges.
I've observed that shortly after stopping the engine, the pipes are very cool to the touch, say within 10' at the header. That's because the air is trapped and the ceramic prevents the heat being radiated outward through the pipe, and instead helps push it out the muffler/tailpipe.
On this bike, I only did the inside because I wanted the raw stainless finish, but my 550 is coated inside and out.
One thing about stainless pipes- they will fail more quickly than mild steel pipes as exhausts. Stainless is more corrosion resistant, but also more brittle and due to the frequent heat/cool cycles of an exhaust, they will not last as long as a mild steel pipe. Mild steel will corrode more quickly, but tolerate the heat cycles better. Ceramic coating helps either pipe with their "weakness" to equal the other metal.
So it's a great treatment for any pipe, regardless of the metal used. I even did the exhaust on my other boy's GS500 which is a Vance/Hines. The factory coating (like a Mac) is crap and within about 6 months, began to fail. Had it shot inside and out, and not only is the damn thing cooler, but now the coating is extremely durable, and is much cooler to the touch.
On this bike (CB500) is treated the exhaust collars inside and out as they will be directly against the head, and I will install and leave them attached. Should also help keep them lasting longer.
Tews, I know you've already buttoned up your motor, but next time you install pistons, have the done treated with thermal reflective coating and the skirts with Dry Film Lubricant (DFL). The purpose of the reflective coating is to bounce the heat occurring in the combustion phase back upward into the combusted air, raising the temperature of the combustion stroke. Hotter air is more HP. You can also achieve the same or better "power" in that combustion event with less fuel. Less fuel equals leaner fuel mixtures, and "Lean is mean" as they say...
The benefit of the DFL treatment is 2 fold. It aides in the life span of the piston by impregnating the skirt with a lubricant, less friction equals more life and more energy as a result of the combustion,
and perhaps most importantly, the DFL helps prevent the engine oil from adhering to the underside of the piston. Think of it this way;
With the thermal coating on top, the heat is not transferring through the piston dome to "touch" the engine oil, reducing the oil temp. The DFL helps further by wicking the crankcase oil off the surface very quickly, again, reducing the heat transference to it. If you can lower the engine oil temperature, then you have a cooler running engine, longer bearing life, less friction, more energy, and so on.
I'm not a racer or pro engine builder, but I've paid enormous attention to and researched these things an awful lot. I've seen studies done (on car engines) and the "with" and "without" pictures of pistons and valve seats is pretty damn remarkable for those engines that use these simple coatings. And the coatings are dang cheap! $60 to treat my pistons. Considering I paid nearly $500 for them, it's a very good investment.
This picture doesn't have them treated with the DFL, as my coater had to order the product and was going to be several weeks before getting to them. But they are shot with it, and now they're at the shop with the jugs for boring and fitment.
I think both Mike R and Brent commented somewhere earlier about their experience with DFL being very impressive too. Due to the nature of these older air cooled engines, I think any little thing you can do to "treat" or "manage" the air temp is a plus. Again, not trying to extract every last HP out, but thinking about the long term lifespan of an expensive engine build. And I fully expect my 20 year old to be "hard" on this bike...
Sorry for the novella
