Originally Posted by jmaxey51

086 = top end pipe
007 = high torque pipe
053 = mid range pipe

but what engine are you wanting to put the pipe on? like its already been said not all pipes work great on all engines.... you can usually get by with the 053 but you could loose tons of run time or just not the right power. i think i have 6-8 pipes and i hardly ever use the same pipe on more than 1 engine... except the JP3, ive ran it on quite a few engine and it work great but some engines im only getting 6 min a tank but i like the power.