NPP conversion for 13 GS
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Joined: May 2017
Posts: 84
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From: Colorado
NPP conversion for 13 GS
So I have a 13 GS with heads, cam, blower, LT’s, catless X pipe and 3” Corsa sports. The damn thing is so ridiculously loud, especially on cold start, that I can’t hear myself think. I want to do a NPP conversion to be able to control the noise levels especially in my neighborhood. What do I need in order to do this to a non NPP car?
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Joined: Jul 2005
Posts: 12,032
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From: Central MO
The NPP mufflers and over-axle pipes from a 2009 or newer car if you want bolt-on installation, and an "NPP in a Box" kit.
My car had a BB PRT system on it when I bought it. It was annoying to me on long road trips so I swapped out like you want to. Install was simple and straightforward. I love being able to control the noise level at will. The NPP mufflers are louder, more brash, and drone a little where the PRT didn't. I generally run open when the vert top is down and once the car is fully warmed up (seems like the exhaust mellows a little after full warm-up).
With your mods I would expect it to be loud any time the valves are open. I have seen posts here where people added a mod to keep the valves from opening completely to modulate the sound a little.
My car had a BB PRT system on it when I bought it. It was annoying to me on long road trips so I swapped out like you want to. Install was simple and straightforward. I love being able to control the noise level at will. The NPP mufflers are louder, more brash, and drone a little where the PRT didn't. I generally run open when the vert top is down and once the car is fully warmed up (seems like the exhaust mellows a little after full warm-up).
With your mods I would expect it to be loud any time the valves are open. I have seen posts here where people added a mod to keep the valves from opening completely to modulate the sound a little.
Last edited by BadAV; May 3, 2018 at 07:24 AM.
