The jp ro3 can take a piston&sleeve from the novarossi kangaroo, jp r9s, 35+21, max xl9 tq. Run the 9 port piston&sleeve in the ro3 and it will have more bottom end than the r9s jp and close to the same top end but much better runtime. Try to stay with a 35+21, jp r9s, or novarossi r1 kangaroo 2009-2010 etc for piston&sleeve and let it rip. The jp ro3 can and will stand the test of time just like the jp to3-t if you can find one.
