Looking for a way to improve the Chevy HEI. After using these units since the seventies, I was not aware of the apparent shortcomings in the design until reading the posts here for the GM HEI conversion into the 258 (which I've been running in 2 jeeps for a while with very good results over the ORIGINAL Duraspark system). I thought my tach was broken when I got my first 258 powered jeep about 3 years ago- it just wouldn't go over 3000 rpms even with all new components in the ignition system and a new Weber carb. Bolted in a GM HEI and Oh-what a difference- it's alive! Now I might be getting ionization, ozone buildup and crossfiring with these distributors, but they are a great improvement over the ORIGINAL Duraspark system. I am not close minded enough to not go back and try out the Duraspark upgrade that TeamRush has so kindly brought to our attention- I am gathering the parts for this upgrade now. My question is, what can be done to improve the performance of the SB Chevy HEI? I understand that the MSD Cap-a Dapt (MSD 8420) is a first step in reducing some of the undesirable characteristics of the HEI. Can the Ford TFI coil be used with the Cap-a -Dapt? Is the Cap-a -Dapt vented like the Ford cap, or should it be modified with a venting system. Does MSD make a Cap-a Dapt to fit the GM six cylinder HEI, so that those jeepers with 258s who have already invested in the HEI ( and maybe gotten rid of their Duraspark systems) can maximize the performance of their investment. Understand that carrying the GM HEI to CDI with an MSD module is not as easy as with the plugin Duraspark system, but it can be done. Has anyone done this with a project writeup? OK, that's enough questions for one post- especially on this apparently touchy subject of chevy /ford ignition comparisons. Let me emphasize that I AM NOT trying to open a heated debate thread on the subject- just trying to get a maximum practical HEI system upgrade for those of us who run SB Chevies and to get the best performance out of the GM HEI for the 258.