I removed my mufflers off of my 2005 gt. I heard its bad for the engine but increases the horsepower and increases the gas mileage. Its sounds like a beast now but is any of this true? I would like to know....

 

I can't really think o any reason this would harm the engine, all it really did was make it a little freer flowing an released the back pressure. I do know that If the back pressure is to low it can hurt performance but I don't think that would be the case with removin just mufflers. And the only thing that I can think of that would Hurt the engine would be if the O2 sensor was after the muffler

 

It does nothing to hurt the engine, and will not affect emmisions. May very slightly increase HP by relieving back pressure. Did you put new axle-backs/pipe, or are you just dumping/turn downs?

 

I doubt it would effect the engines preformance at all.

 

I did the first muffler delete in 11/04 when I got my 05, 180K later & I still love it!!