header id sizes

[joseph puglia]

Anyone done any testing on header id's? Larger/smaller than stock, what differences does it make if any. ( mainly for larger motors)

 

[Buckshot]

Tapered ID of around 1.5* work good with small end same ID as the case snout.

 

[Joe Warren]

Try to stay atleast the same ID as the lead in pipe of youpr Tuned pipe. It would be best if you telescope over it..... Not in it........ Larger ID head pipe pulls more Prop.