I use K&N oil filters and air filter........oil filters are good never had any problems...air filter lets alot of air through with the yoshi system had to up the fuel injection 10% everywhere....but it stops all crap getting in the engine too....some other performance filters may let more flow through but might not actually filter as well and let stuff into the engine

Best of all with K&N air filters...they do aftercare kits to clean them too...which is better than using parafin IMO.