I use to run on the Viper........ APC 9X8 on a Evolution 46 NT & muffler, 9X9 on a 45 YS & pipe, 9X6 on a OS 32 & pipe, 9X10 Webra 55 (round black head) & red Jett muffler. 10X10 OS 55 AX &muffler.
The header looks long in the O.P. so it will pull that pylon 8.8X9 @ 16.500. If your having fun, don't mess with it. There may be more speed with different SPORT props, but you will have to cut the header and experiment. Without doing a thing except tweaking the needle maybe I throw APC 9X8 on it.