Sincereone

Hello I'm looking into buying a buddy club dual pro spec exhaust for my Ap1 S2000. Question I had is does anyone know the diameter of the piping? From what I searched i saw 65mm... Also what size test pipe would u suggest? From videos I've seen some have ran 60mm test pipes others 70mm. I know it's best to match the sizing so was wondering if anyone has/had one and what has worked best. Thanks for your input appreciate it very much.