did some searches and research and have read all about the gains and how the plenum and plenum spacers work. i was just wondering what kind of new sound they make when driving and under WOT. and would it be lounder with a CAI

 

not sure with a cai, but my with my popcharger, i noticed it was a bit more grumbly and a tad bit louder.

 

wooooooooooooooosh....

 

loud and like a muscle car sound.

 

A lot of people report the plenum making the intake louder. I installed it with a Nismo CAI and didnt notice that much difference in the sound. Maybe a little louder at high RPM's.