Welcome to the forum and congrats on the softail! I have an 04 standard also.
I know a few people who run regular gas with out issues, but I just stick with premium.
I use the HD filter, works fine. Do some reading in the oil forum on that subject and
if you feel brave, post a question in there...LOL

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04 softail standard
Baisley-Axtell 117 - Baisley pro street heads - Baisley hybrid injection
Bob Wood TW-8 - Darkhorse crank - P.M. Hydraulic clutch
P.M. 240 Phatail - Roland Sands Design air filter
P.M. Villain wheels-rotors
Paint by J. E. Illusions - Powder coat by Sumax
Builder - hdryder