What is the difference in the length of these two headers, or does anyone know of another temporary compatible header that would fit as well as any known legth differences.

Thanks

 

I am pretty sure that most b16a headers (99-00 Civic Si, etc) would not clear the oil pan of the B18C. You could use any B18 header on the your b18c though, from any model Integra 90-01. You might have to customize the exhaust length, but they will all bolt to the head and should clear the oil pan fine.