I found this post on an evo 8 forum on the net, it shows how to make easy nonfoulers for test pipes. I bought used set today and I only got one non fouler, $5 is cheap for what someplaces are charging for these little spacers. Heres the link:

http://forums.evolutionm.net/showthread.php?t=215795

Be careful with those non foulers I am almost certain that the 42009's are to shallow for the O2 sensor probe. We have always used 42002...

Tony

Be careful with those non foulers I am almost certain that the 42009's are to shallow for the O2 sensor probe. We have always used 42002...

Tony

thanks, It looks like he used two double stacked though? Ill check if I try it, info is GREATLY appreciated

they shouldnt cost that much from kragen, pepboys, autozone, etc.

there is a diy in out forum for non-foulers.

less than $5?? Its basically $5 per side because you have to double stack them. Ill be doing this as soon as I get my new engine from Infiniti Riverside.

These are extremely cheap to make. I made a setfor my S4 with no cats and they worked perfectly. Go to Pepboys or Autozone and purchase the correct size Spark Plug Non-Foulers. You may have to drill them out a little for the O2 to fit in.