Here is a video I took a couple years ago after I installed RarlyL8 headers (with heater boxes) and hooligan single outlet muffler. I also have a K27HFS, and a TiAl with 1.0 bar spring TK IC and Leask WUR.
I used a gopro with a remote microphone taped to the bumper right over the exhaust to get the most realistic sound I could without all the wind noise.
Turn up the volume! If you have a desktop with a subwoofer sound system, use that to get a good idea of the real sound.