What are the best convertors? PTC, B&M, Dynamic, Turbo action

I've used PTC with real good results. All the mfg's you mentioned build decent converters. To say one is the best is hard to prove because your not always comparing apples to apples. As mentioned, a real good converter isn't cheap so don't expect any $200 off the shelf converter to give you optimum performance. My recommendation is to call and talk to the different companies and get pricing. Personally I have had such good luck with PTC I don't call others. They build a great converter at an affordable price