This is an automotive application but you will be surprised how much you can flatten an exhaust header pipe without compromising power
https://www.facebook.com/watch/?v=152724102049876
Hi from West Gippsland, Victoria, Australia.
After 24 years in the aviation industry I am finally working towards getting my RPC.
Hoping to build myself an aeroplane in the not too distant future and get out flying as often as possible.
Cheers
Jake