Stay away from the M16. If you get a good one, it is a good one but the bad ones dont last a gallon and you have a 50/50 shot. I have owned two and got one of each and there are many others with similar stories. Hot Bodies .18 will not last, nickel sleeve and only a high speed needle. For any performance it has to be ran at 320 + degrees and I only got a gallon out of the one I put in my Kyosho ST. XTM .18 I have heard nothing but good things about but I have not gotten one yet. My personal favorites are the OS .15 CVRX or the Fantom FR.15 of you don't want to spend the money for the CVRX. Also have to mention the Trinity Picco .15 for about 150, I have the .12 and it screams and every one I know says the same for the .15.