Heyboer, Edcor, Magnetic Components, Mercury all make good stuff and the Magentic Components transformers are an especially good value if you purchase them as a bundle. But the Weber and Hammond transformers spec-ed in Dave Hunter’s original bill of materials work great in the 2Stroke too. I’ve built the 2Stroke both in the original stock form and with upgraded parts and I have to say, the original is pretty darn good with the less expensive transformers and speakers. IMO