Engine in question is an fms running a ofna 086 but don't know which header , its possible about what you are saying with late combustion timing but I don't believe it to be the case as he is running SUPER hot plugs .

The ofna 086 isn't exactly the highest quality pipe on the market and gets plugged up pretty quick , I have ran many of these pipes to know what they do . They run phenomenal for the first gallon then build up carbon and lose performance , as does any pipe but these ones especially .

Hope this helps

Btw , I don't recommend usin an 86 based pipe on the FMS