yeah it uses the 450r filter and its tucked up really high in the chassis, I'm more concerned about fitting under the seat than I am about brake caliper hitting it. I did have to go to a tapered filter shape instead of a cylinder shape. i.e. so UNI won't work, those guys refuse to do a tapered filter, but No-toil, K&N, & S&B will be good filters as well. I designed it specifically for a 4.5" opening K&N filter, RU-4740.