I am currently running a si/so 3" magnaflow on my 09 Sierra with a 5.3. The other day when I busted out my 3rd cat it sounded awesome with the tailpipe and muffler removed. I was wondering if i replaced my muffler with a strait pipe if I would lose performance or mpg? I also thought about running a dynomax bullet for a louder sound. Any opinions?

 

Im thinking you might lose a little of both,and I have a feeling its gonna be ungodly loud lol.I would at least run a muffler dumped right before the axle.JMO

 

get a cutout...idk why anyone would want to run wide open exhaust all the time with no way of toning it down other than to have to get it welded back up. cutout gives you the best of both worlds

 

You won't lose any performance or economy for having no muffler. However, coming from someone who has owned a DD with no exhaust on it, you'd better have either a loud stereo system or some earplugs, or you're gonna be miserable on long drives.

 

If I read the original post correctly,he is also running no cats,im thinking he is gonna loose a little bottom end unless he is tuned for no cats.You will probably be ok if u run the magnaflow like u have now and maybe dump it after the axle if u want a little more sound.I wouldnt run straight pipe if I were you.I know its all relative,but Im running a stock 4.8,I had a Aero Turbine muffler on my truck and when I would climb hills it would downshift to second and run at 4800 rpm to keep the cruise at 75 up a hill,I changed to a regualar flowmaster 2 chamber,and its never been past 3000 since.On the same hills.Just my experience with my truck.yours may vary.

 

I am still running 2 cats, I just gutted the 3rd cat that gm installed starting in 2009. I think I am just gonna replace the Magnaflow with a Dynomax Bullet. I am currently using the factory exhaust pipe.

 

oh ok i thought u were running no cats at all,then u probably wont see any performance diff, but it will definetly be alot louder.Wow I didnt realize GM put three cats on these things lol.

 

I have a 2005 chevy with the 6.0 and i run no muffler only cats and a x pipe it sounds great i lost no performance gained some with the x pipe only lost mpgs listening to the pipes

 

i have an 02 yukon with a 4.8 and dual 2.5 in strieght pipes not as loud as my 03 25oohd with 6.0 and dual 3in with dynomax bullets