sound is minimal with just the primary bypass.

the X=higher pitched sound, think ferrari....

the Cross over=Low Sound, think muscle car....

i prefer the tuned higher pitch sound as it does not drone as much.

the primary creates the sound... the hack allows it to be heard.




i have had both primary's on my 997.2 and both the hack and the secondary bypass... the combo i ended up with now is the x pipe and the hack.