Update: daytonimport.com Sales emailed me again, they say their product is rated to 400 degrees[B]. They mention that if your intake manifold ever got that hot it would mean that your engine had blown up. In addition, I believe the same product from outlaw engineering is rated to 300 degrees[I] - "The ThermoBlok spacer material also exhibits high stiffness and compressive strength, can withstand temperatures up to nearly 300°F, and has a thermal expansion coefficient very similar to aluminum to increase sealing capabilities.". Again, to me this indicates a quality product (100 degs higher than a proven product). I'm planning on getting one off Ebay and installing soon, I will post the "results" (non-scientific feelings about before/after differences in performance. One other thing, all you get from these guys is the gasket, absolutely nothing else. They say to just use your stock studs.