Thinking Exhaust Cutout
 

I know there's several on this Forum that have experience with cutouts. I've been interested in one for some time now and am thinking maybe spring next year. It would just be an addition to the current setup I have - stock exhaust manifolds, cat, resonator and MagnaFlow cat-back system. Not looking to get super crazy, I just want more sound.

It appears QTP or Badlanz are the recommended brands. If I install just the manual cutout and run it open all the time, would that be too much? I know the only way to close it up would be bolting on the cover plate but the car only sees about 1k miles a year so I think, at this point, I'd be fine with it open all the time unless it's obnoxiously loud. Just looking for input on that.

I mean, thats arguable.. To each their own you know?? Me personally wouldnt do a manual cutout just because I would want the control without having to get under the car, exactly why I havnt done it yet.. Although I wouldnt mind constantly hearing a loud v8 but in that case I would have a totally different setup than you and therefor would have no need for a cutout..

The reason I was thinking of ditching the electronic portion was due to cost but Badlanz kit is actually decently priced compared to QTPs.

I run a cutout on my LS4 gxp (DMH cutout, Y split installed in place of resonator) and it has been on for about 8 years and 50k miles. Gets opened and closed a few times each week with zero issues.

I also have a cutout on my monte (Jegs brand, bottom of downpipe 'elbow' cut off and flange welded directly to bottom of elbow for a straight shot out of the downpipe through the open cutout) but it has only been on about a year and less than 1000 miles.

There are a few things that make a big difference in sound:
-How modded the engine is. A heavily modded engine making a lot of power with a big cam will be way louder than a stock or bolt on engine.
-What exhaust components are located ahead of it. Positioning the cutout ahead of everything is loudest. The more components in the way (cat, resonator, etc), the quieter it is.
-Where the exit is facing. While this makes a little difference to those outside the car, it makes an enormous difference inside. A cutout back by the muffler with the exit pointing away from the car (like the exhaust tips do) will be the quietest inside. It gets much worse if you're dumping under the car, especially if it's pointed straight at the ground. The cabin will have a lot of resonance doing this with the sound waves bouncing off the ground then back up to the floor pan, etc etc.


Not sure if you still have it enabled, but one thing unique to the ls4 on this platform is the cylinder deactivation. Running in 4 cylinder mode sounds pretty awful while it's engaged.


As far as just running a block off plate, that's not a bad idea for starters as long as you leave enough space to mount a cutout later. I think it's especially true with how little you drive it - at 1000 miles a year, id think anything short of a funny car dragster would be tolerable, lol. I like having an electric cutout for two main reasons:
-it's technically illegal and is speifically called out per our DOT out here (even if it's after the cat), so Id like the ability to close it if I ever get pulled over.
-being that both my cutouts are under the car, it can get annoying on longer drive, especially if you're just sitting at one rpm for extended time.


One last point, do be careful about where the outlet is pointing as there is a lot of heat expelled (and potentially flames as well depending where it's at in your exhaust).

@bumpin96monte, thanks for your post. That's exactly the type of response I was looking for, lots of good info there.

I think having the ability to close it is a good option to have. Doesn't need to be open all the time - I really want it open and louder for shows and I could see occasionally while cruising. If I need to do a few more things to the exhaust to get the sound I want, like a cat delete, that may be an option too.

I suggest getting a qtp electric one. Having the luxury of open and closed is wonderful. I would also mount it either before or after cat depending on how crazy you wanna get. My Moto is if it's electric might as well make it as loud as possible when open since the option to close and be quiet is at the push of a button.

At this point I'm thinking of doing a cat delete and having the cutout installed somewhere in that new section of tubing, somewhere before where the cat usually would sit. I'm leaving the resonator for now because I'm not a fan of the raspy exhaust sound. Anything I need to be aware of when doing a cat delete?

Straight pipe, don't just hollow it. (Which I believe you are doing). And you'll need to do a retune for CELs and so the car doesn't keep dumping fuel to get the cat up to the temp, since it's no longer there.

Also be aware you will have VERY dirty exhaust tips afterwards.

Totally agree here