Yeah I had a sissybar n rack fitted to keep the other half happy at a cost of over £400 !
Don't know about the sportsters but with the V rods you can change the silencers and exhausts but if you change the air filters you have to get them tuned also if the replacement exhausts have little if no back pressure then there is a loss of power
Maybe you just need to get a sports filter and a tune believe HD call it a stage 1 tune (exhaust/filter/tune)
Seems to be the choice for most of the air cooled Harley's
Hope it's dry tomorrow so at least I can take it up the road