Are eBay silicone radiator hoses any good for a Mazda RX-7 FD?

The source material's warning about cheap eBay silicone specifically concerns intercooler couplers, not radiator hoses: cheap silicone there was noted to cause "tons of problems down the road," though some builders have still had success shopping around for specific pieces ². For radiator hoses specifically, there are a couple of known-good alternatives available:

• RX7.com Hoses: These are built as an exact copy of the original Mazda hoses to ensure a perfect fit. They are high-quality and typically run between $79 and $95 for the upper and lower set ¹.
• Godspeed Project Hoses: This is a budget-friendly option, typically priced around $45 shipped. They are made from 5mm thick, 4-ply reinforced high-temperature silicone and are rated for pressures up to 128 PSI and temperatures from -65°F to 350°F ⁷.

A Note on AST Hoses: If you are planning to replace all your coolant lines with silicone, be aware that there are no direct-fit aftermarket silicone hoses for the Air Separation Tube (AST). To use silicone there, you would need to route reinforced straight hose carefully so it doesn't kink, potentially using a spiral stainless steel wire insert to help it hold shape. Otherwise, it is best to stick to the OEM Mazda rubber hoses for the AST ⁴.