BadAV

I swapped the BB PRT exhaust that was on the car when I bought it for an NPP yesterday. I have not installed the NPP in a box kit yet so it's currently running open. The PRT is louder at startup and idle than the NPP, and is slightly louder when running steady throttle at highway speeds. Sound level is about the same when stepping on the gas to maintain speed on an uphill incline, but the sound is different. The NPP has more "felt" sound, starting to border on resonance (drone) than the PRT. I will be running the NPP open most of the time but it will be great to be able to push a button and shut the noise off for long highway trips. I WILL miss the nice pops and cracks that the PRT had during deceleration! I will be putting the PRT in the for sale section, probably in mid-July. We are in the process of packing our home up and moving so I won't have time to clean it up and post it until done moving.

Dcasole

I love my NPP 'S just because of the ablity to close them when I want

They still pop and cackle a good bit ....

Dave

Seadawg

You should get the same decel sounds with the NPP open

Dcasole

BadAV

Not nearly as much as with the PRT. It was one of the things I loved about them.

jimy

I put the NPP mufflers on my 07 and ran them open for over a year. Sound was great but I wanted it a little louder. So I decided to install headers, catted H pipe and NPP in a Box. Much louder and much quieter. Love it!