Has anybody ever run a Moki 210 on a pipe? How did it respond to the pipe? What prop, fuel etc. were you using? THANKS!

Look up long riffles on here. He raced them and would pull a 16x15 apc at11,000

Will do. Thanks!
That is pretty impressive performance!

that is on 50% nitro and a little work done on the head

Was the work on the head done to reduce the compression ratio?

Usually higher nitro works better with a more cone shaped combustion chamber where low-mid nitro content works better with a more bowl shaped combustion chamber. With lower nitro fuel you also generally want a wider squish band with a slight angle and for higher nitro fuel a narrower squish band with a steeper angle. Note - this is only what I've read, I have not tried it myself but it makes sense. My Jett's are setup to run 15-20% nitro and have a cone shaped chamber, whereas an Italian SuperTigre has a bowl shaped chamber which is setup to run 0-5% nitro.

Do the Moki/Mark engines use a button head or one piece head?

Yes what 1qwksport2.5r stated about combustion chamber shapes. But also the compression ratio changes. Low nitromethane glow fuel means you run a higher compression ratio. But higher nitromethane levels means you run a lower compression ratio.

But one thing to consider is the fuel consumption of a 2.10 glow engine. At full throttle it is quite thirsty. But with a tuned pipe that could double the amount of fuel it needs. So it could become quite spectacular for the amount of fuel needed to fly full throttle for 8 to 10 minutes.

for 8 to 10 mins you will need a 40 ounce tank.

Yeah that sounds about right.
My 26cc gas engine with a tuned pipe was sucking the fuel out of the tank quite fast. Sort of like pouring out on the ground kinda fast through a tube. You could watch the fuel level go down while you watched it run at full throttle. And it was running on gasoline too.

It might be worth it to test run the engine on a stand to get a fairly good idea of its fuel consumption. It would help one plan as to how much fuel they need to fly it with.

Planning on flying aerobatics; so won't need WOT more than 40% of flight time. I'll start with a 20oz tank.

20 oz will be the very very minimum that you will want. I have a 2.10 with a regular muffler in a Byron's Glasair and I can fly safely for 7 minutes on a 24 ounce tank. That leaves 2-3 ounces in the tank so that I can have a go-around, or loiter and low throttle if I am waiting to land. I almost never use full throttle since the plane is moving plenty fast at 50-60% throttle. Take offs, verticals, and loops are about it for WOT.