Sunday, I spoke to a couple guys that have raced with Saito engines out at the SAM field:
Tom has run Saito .72 and .82s in Bronze, and used a 1.25 in Silver. He invert-mounted each of them. He stated that all 3 leaked out of the carb, so he had to leave on hemostats until he was ready to start the engine. He used 30% nitro fuel, and did not use fuel Tees in his setup. He stated that he "had to be right on the pylons to be competitive" [on break-out time].
Steve used a Saito .82 with 20% nitro in Bronze. He was busy running our Outlaws race, so I wasn't able to get more from him than that.
But, I was able to get quite a bit of information from David, who was running the same engine you are. David invert-mounts his Saito 100 in his World Models P-51. He uses 30% fuel and an APC 12 x 12N prop, and was competitive with this configuration in Silver, last year. He said that he would usually run just over the 2-minute break-out time -- usually about 2:05. Just when he thought he didn't have to ever worry about breaking-out, he did. He never experienced ANY leaking, and did not need to use hemostats at any point -- not even during fueling. He stated that he "didn't do anything special. It ran perfectly. I was even able to move the tank back to the CG without any fuel draw issues." He loves that engine. "It is reliable, easy to tune, and get parts."