Most times not on a Completely Stock Engine.Even with a EBR or Other Race Style ECM. They are nice to have due to keeping the pressure somewhat constant.If I'm running a Stock Engine with a Race ECM (which)is not much more than Maybe 10 to 12, extra horseower I haven't had any issues.The ECMs we buy from Buell Etc.. This does not include programable ECMs. Now if your putting a High Volume Fuel pump for, Drag Racing yes. Say it's for Track racing like I do then yes please install one for keeping the pressure perfect and constantly accurate .Really depends on your Engines Build. You will also need a liquid filled pressure guage and Braided fuel line for safety.Make sure to get an adjustable(Regulator) if you so decide to go ahead with that.NOT to mention it does look good on any bike when you put on some Guages, even if it's for looks it will also come in handy for the some times Quick diagnosis of fuel/oil/and Temperature issues. I Have the Liquid filled, Volts/Oil/Fuel/and Temp.,Guages on my Street bike as well & costly but necessary on any bike,[my opinion]with a race bike due to the money spent.Make sure to pick up a fuel pressure instrument(checker) so you can set it properly for the bike to run correctly.*Jimi