has anyone put the efi conversion kit on? is it worth it?

 

I can't say from experience that it is worth it or not but from what I've worked with it isn't all that great. It's nothing but a headache when put onto a larger engine like a zz4. The truck I tuned passed NJ inspection and that's without EGR! Still too much work and I honestly don't know why it liked what I did, I only did what it wanted.
I would look into a swap that gets rid of the older c3 ecu for something at least at the p4 level. A 7730 TPI system would work very well for any mpfi setup you bolt together. This is of course only good with a completely stock 350 L98, else get into chip burning, it's the only way .