My secondary ignition's wires are labeled "7mm Hi-temp radio suppression cable". I believe these are provided with the kit direct from Sonex. I get no noticeable ignition noise from this ignition. Do you have the same wires?
I get buzz of clicks that I can almost count (10hz?) when my primary ignition is on. When I'm receiving someone relatively close (10 miles?) I hardly notice the clicks. When a distant transmission breaks through the squelch (or I intentionally open the squelch) then the clicks are about as loud as the transmission (the automatic gain correction of the radio amplifies everything so I can hear the transmission and in the process makes the clicks more audible). I don't know anything about the ignition wires with this ignition--they seem to be permanently attached to the magnetrons.
The Autolite 4163 plugs Sonex recommends are suppressor plugs (
http://www.autolitecatalog.com/PartDeta ... =A&pn=4163). I believe this means they should have less ignition noise than non-suppressor plugs. Are you using these plugs? On your previous post, fastcapy pasted some correspondence from MGL that mostly doesn't match my experience with the Aerovee ignition systems, but that suggested the use of "spark plug caps containing damping resistors". I would think this would be redundant with 4163s, but maybe not?
viewtopic.php?f=29&t=1626&p=11686#p11898Which ignition gives you noise? If it's the same on both, I suspect your noise is coming from something else. What type of antenna do you have and where is it mounted? Does it have a good connection to the ground plane? Do you know anyone who can do a SWR test of your antenna installation? If you can transmit fine, I might skip the SWR test.