What ever you do, don't let price be your guide. I know that $$$ are hard to find, but a poorly spec'd converter or a price only converter can be your worst nightmare. Properly applied, they're great, poorly applied a bad, bad performance investment.
Your converter supplier should ask you a lot of questions before letting you know what is the RIGHT ONE FOR YOUR CAR!!.
I worked in the industry, and saw lots of fellows get the wrong converter for their particular application. I've attached a spec sheet we asked customers to fill out. BE TRUTHFUL about the information you're supplying and your converter supplier will get your the one you need.