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Old 01-03-2012, 08:01 PM   #33
Fraxum


 
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A quiet exhaust solution

Lately I have seen a few posts here about having long tubes with a semi-quiet exhaust system. So i want to share my experience with my LS3 and a similar quest.

Some of us like to hear our motors but in a subdued way. While we like speed we also want to take our cars on long trips with our families and be able to listen to and enjoy music and books on tape. And there is a special kind of fun in having a fast car that doesn't sound fast or attract attention.

My car is an LS3 and i was looking to add long tubes and high flow cats while avoiding a loud exhaust and hopefully not spending a lot of money.

For starters I found a great deal on a set of used 1 7/8 Bigflow stainless LTs with a pair of high flow cats. I installed these myself in my garage. I started out by keeping the stock catback. I was hoping that this combination would keep things quiet while spending the least dollars.

One strange thing about the BFE cats is they are longer than most and require you to cut your stock sized cutback to install. But since I would only be cutting the stock pipes, I did not see this as a problem.

My results with the LTs and stock cutback:
The Good -
  • Almost as quiet as stock at lower RPM with a nice little growl.
  • No drone.
The Bad -
  • De-accel popping is very loud
  • Wide open at higher rpm is very loud with a very annoying slapping sound
Since it was quiet at lower speeds I did not mind it being loud at high rpm. But the high speed sound was awful to my ears. It had to be fixed.

I did not want to buy an expensive cat back and then cut it to install. So I looked around and decided to install one of the quieter axle-backs, the Magnaflow Street. This seem to be ideal. It would keep the car quiet, while saving some weight replacing the huge stock muffler cans.

My results with the Magnaflow axle-back:
The Good -
  • The tone was deeper than stock
  • The sound was much better at high rpm
  • De-accel popping was much quieter than before
The Bad -
  • Drone.
At speeds between 55-75 the thrumming, while not overly loud was very tiring on a long trip. And with 4 people in the car the drone was especially bad. More had to be done.

I put up a post talking about the drone and a vendor suggested I try the Magnaflow X-Pipe. This pipe (which looks like a muffler) replaces the stock LS3 H pipe and is also part of the Street Series cutback.

So I bought the pipe and had it installed in a local muffler shop today. It replaces the stock H-pipe and leaves the stock LS3 resonators. While they were at it they fixed a couple of exhaust leaks and let me know one of my sway bar brackets fell off. They also moved things around to give me a little more clearance over the rear tunnel cross brace.


My results with the X-pipe:
The good -
  • Quiet at low speeds
  • A nice deep tone at idle
  • De-Accel popping is almost imperceptible.
  • Quieter at high RPM
  • No drone.
The bad -
  • Some might think it too quiet (but not me).
Overall I would say my car sounds about 10 percent louder than stock at low speeds and 25 percent louder at speed.

For anyone looking for a quiet LT set up I can recommend LTs with the Magnaflow Street Series products. With the X-Pipe install cost I ended up spending almost as much as a full cat-back. If i were to do it over I would probably just buy the Street series cat-back and then cut it to fit the BFE cats. However then I would lose the LS3 resonators which may be the things that makes my setup work for me. Then again they may be contributing to the drone.
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