I was using my old housing to test fit the magnets and it seems like it was easier to keep them in place if they were the same polarity wise. I used some duct take to hold them in place until I got them all on and tightened the hose clamp.

If the were alternated polarity, they wanted to jump to each other.

I could be wrong as to same or alternating polarity, but flipping them around made a difference to attract or repel.

IIRC, same polarity repels and opposite attracts

BTW, I bought a 2.25-3" clamp and it is fine

Just a bump for a good simple bang-for-the-buck mod...

Keeps and trace-ferrous debris from going through your filter and wearing your engine.
My most recent filter check after about 5k miles:
http://986forum.com/forums/uploads02...1523307273.jpg