No brainer dude....Picco. Balanced crank, dlc, and ceramic rear bearing.
R5R is good too. It doesn't lack power at all. Depends on the pipe. If you pair it with the picco 2133 it's a monster at bottom and top...especially bottom. The 2166 is the next best option (same as REDS 2143).
It's a good truggy motor with that pipe.

Btw...in have both motors and both pipes.

The picco 2099/ reds 2104 is a smoother pipe with better runtime than the others above. 2133 has the worst runtime but makes stupid power.

You can't go wrong with either but they are so close in price just get the Picco.

Oh...the REDS had a 2 piece head design also...