I made up a new can with a little longer pipe attached. I used a 12/9 apc prop and cut 1/2 inch at a time( should have stuck with 1/4"). 1st cut got + 200 next cut another 200 next cut lost 150. Then put on the 12x8 and was up by 600 over the 12x9.
I will I'll try to attach a picture of my setup with the three cans I used. I slid the short can all the way up to halfway around the header radius on the way up it peaked and then went back down a little. I still was a good bit lower than with the other two cans which are pretty close to each other.
75 tower , 15% nitro, 18% oil, 50 deg f
11,650 - 12x9 apc
12,250 - 12x8 apc
12,700 - 12x7apc
13,200 - 11x8 apc
13,290 - 12x6 apc
13,700 - 12x6 MA SIMITAR
13,500 - 11x8 Revup wood
13,900 - 12.25x3.75 apc