Quick Exhaust Question
 

I've got a 94 jdm gsr in my 92 hatch cx. I have a stock header but with a tanabe medallion exhaust on it. Currently I have no cat on the exhaust so it is just open. I'm going to purchase a cat/test pipe but need to know the measurement between the header and where the exhaust starts. The weather is crappy here and I haven't been able to get under it to measure it so I was just wondering if someone could give me the measurement? I'm thinking 17 - 18 inches between the two but would like something a little more precise. Thanks