He runs his TT07 on 25% nitro and it does well ,,the Norvel .074 is a MUCH more powerful engine and lighter too,and probably louder,, it is said to have the power of a .10 size engine,,where as the TT07 is a good reliable engine with a good idle but not as much power..nitro is very common here and we tend to experiment for the best %,the higher the nitro the better up to about %35 then you start wearing things out faster than normal, mostly we run between %20-30 nitro in the small engines and about %10 in the larger .40 size engines..Rog