I have a professional built custom Bearcat. On top of the list would be the custom over the wing scale exhaust that is attached to a DA100. We sent exhaust and engine to DA and they dyno tested the exhaust. DA was surprised at how well it preformed. It actually out preformed factory exhaust, more RPM and HP. It has Spectrum duel with life batteries. Smoke. I can get the build list if you are serious. We bought the best when it went together. Please give me feedback. Thank you.