Tried starting the 550 and the 1100 today. What I know. The 550 is a rebuild project from ground up. Compression 1-4 all about 58 lbs. on the other hand the 1100 She barks like a big dog. Ooohhhh mmyyy word sweet baby Jesus that thing is all that and a bag of chips. Next step cables and hoses. Some wiring Valves And a bit of the church. Clean out tank We will go from there.