I have about two gallons on my WS7 and 523, my C6 has maybe 7 gallons and still an animal. I changed the rod at first of the season but thats it. I use sidewinder fuel and have had good luck. If you treat it nice you should see 8 gallons or more. I have read other forums about guys getting 10-15 gal on a motor. RB has a good forum also, lots of info
http://www.rbproducts.com/cgi-bin/ub...ultimatebb.cgi