I don't know the size of the W-R adapter, but the one most people are suing is from
www.spmotorsports.com IIRC. But! Just so you know the K&N does not fit perfectly for it. If you are looking for a nice fit and maybe a turn or two of the screwdriver, thats not how it works. You actually have to tghted the hose clamp that come with the filter alot to make it fit tight and the way its suppose to. It's easiest to put the filter and maf adapter together outside the car, then put it in the car.
