Custom tuning with cutouts
Thread Starter
Racer
Joined: Aug 2013
Posts: 434
Likes: 109
From: Torrance, CA
Custom tuning with cutouts
Is it harder to tune a car that has cut outs and I'm wondering if it is tuned with the cutouts open or closed? Is there a problem with it running lean or rich depending on the cutout open/closed position?
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,631
Most of your restriction is from the OEM cats, and even the OEM muffler really don't have a resistance problem isntead.
So cut out after the oEM cats, will not make a difference in the tune,
If you have high flow cats, then will not matter if the cut outs are pre or post cats isntead.
Truth is, your not picking up any HP with the cut outs, and all your doing is making the car sound like a loud dump truck isntead.
With the NPP mufflers, it's claimed that you pick up around 6hp over the stock mufflers, but when your making over 400hp at the motor, you really can't tell the difference instead. So tune will be the same with the cut out open, or closed, and if you have a tuner that is showing you that you are making huge gains with the cut outs open, they are tricking the dyno to make the different readings isntead.
So cut out after the oEM cats, will not make a difference in the tune,
If you have high flow cats, then will not matter if the cut outs are pre or post cats isntead.
Truth is, your not picking up any HP with the cut outs, and all your doing is making the car sound like a loud dump truck isntead.
With the NPP mufflers, it's claimed that you pick up around 6hp over the stock mufflers, but when your making over 400hp at the motor, you really can't tell the difference instead. So tune will be the same with the cut out open, or closed, and if you have a tuner that is showing you that you are making huge gains with the cut outs open, they are tricking the dyno to make the different readings isntead.
Race Director
Joined: Oct 2005
Posts: 14,555
Likes: 1,255
From: Saint Albans, WV
Loud dump truck huh? You’re usually pretty spot on with your info but you missed this one by a mile!
