I'VE HEARD THAT SOME OF THESE STRAIGHT-THROUGH MUFFLERS LIKE MAGNAFLOW AND BORLA ACTUALLY DECEASE TORQUE AT LOW END DUE TO LACK OF BACK PRESSURE AND THIS HURTS GAS MILEAGE. HAS ANYONE ELSE HEARD THIS?

 

Sometimes you will lose a little, and you can definetly feel it by the seat of your pants meter. Putting after market exhaust systems alot of time moves the power band to different rpms. so what you might lose in lower rpms, you make up in mid to high rpms. I dont think you lose any gas mileage, its just that the truck sounds alot meaner and you tend to put you foot into the gas more, giving you bad gas mileage. If you drive normal, you might even gain a little mpg's with an after market muffler.

 

Modular engines actually produce better gains with flow-thru type mufflers rather than chambered mufflers.

 

I have a borla SIDO and 2 high flow cats. I've made my exhaust as free flowing as possible with out headers and I cant feel any power loss I don't have dyno runs but I don't think the borla and magna flow high flow cats hurt the low end . BTW the top end is "sick" Along with the sound!

 

I went from cat-back duals with a Flowmaster 50 Series muffler to single exhaust with a quiet muffler and I can definetly tell that my truck gained lowend torque.
It used to have a little bit of a bog off the line and then it would come to life at about 2,000 rpm but now the power is smooth and even all the way from idle to 5,000 rpm.

 

I didn't notice any change when I did my exhaust.

 

i noticed I had more power when I put on my AERO exhaust

 

Power loss because of open exhaust is a myth. If backpresure produced more power then Top fuel dragsters and Nascar would run mufflers. They try to get every HP out of those cars as possible. We have dyno proven that better flowing exhaust makes power all across the power band.

 

Depends on the motor. Some engines will loose big torque, but when torque isnt your need then who cares. Some engine it will cause detonation too, which of course can be tuned out. It does depend alot on your TUNE and type of motor.

 

I believe they have low end losses too but the top end that they gain more than make up for it. After all, all Top fuel and nascar are top end motors.