I have been flying my asp 52 today and my grinding and raising of compression allowed me to run straight faI fuel with only a 200 rpm loss compared to stock engine on 15 % nitro. when I switched to 15% I gained an additional 100 rpm over the previous 15% readings.. So it works, just not to the degree I was hoping for. I think I will go back inside the engine and dremel some more since I left one port untouched. All in all 13100 rpm on asp xls 52 with 12.25-3.75 apc on o% nitro is quite good. fuel cost is under half of running 15%, so I`m happy so far. Next step is either to put on my rossi tuned pipe or ordering a tower muffler. Last but not the least, a buddy of mine ran his 61 fx today on the 12.25 apc and 15% fuel. This combo did 13100 bone stock, after removing the baffle and drilling the outlet to the maximum inner diameter rpm`s reached a very high 14000 peak. Alot of free power as you can imagine