I installed the Transfer Flow 50 gal. with TraxII system and had the pleasure of using it when we went to the Georgia Good Sam Rally in Perry this weekend. We traveled over 475 miles round trip and it was great not having to stop and fill up. We looked at the RDS system but decided to go with the TF. It is I believe the only one that is street legal and has completed all of the paperwork and testing. Shipping $200, install $300.00. Yes it was expensive but worth it IMHO. Good luck on your decision.