So I now have 4 tanks through the S852. It was a complete joke to start (OFNA Truggy box running 4s LIPO) without the shim, so I didn't bother adding it. So far so good. I had to wrap the head to get it up past 200 for those first 3 tanks, but it maintained VERY VERY well.
Keep in mind this is the first engine I am breaking in from drop 1 of fuel. Prior to this I have only broken in a freshly pinched sleeve.
After Tank 3 I unwrapped the head (using a 1/10th foam), and it's just humming along so far. Boring even ;-) Tank 4 I finally started using some quick bursts of 1/4 to 1/2 throttle....and it's just running awesome thus far. Ambient temp is dropping outside, so I stopped at 4 tanks and I'm impressed so far.
I've only adjusted the tune a little bit from factory, and while I haven't driven it yet, or gone full throttle....it seems to be running very nicely. I think the LSN is at 2.5 - 2.75 turns in from flush now and the HSN I only leaned maybe half a turn so I'm at @ 1.5 turns out from flush.
This engine/pipe combo does sound pretty meaty! I cannot wait to get this thing out on the track already!