How many of you have run your 5.4 with no muffler, just the cats? What's it sound like? Thought I'd read where it's not bad with the cats still on. Performance/mileage change?

 

I cut my 40 series flowmaster off a few weeks ago. I had a y pipe installed instead, I love the sound, I have not noticed any milege diffrence or performance change from the flowmaster but sounds much better than the flowmaster. ps I also have an airraid which might have something to do wih the sound.

 

I souhld beable to tell ya in a few days, but my setup will be true 2.5" duals from the cats back with no mufflers. My buddy ran his 98 4.6 with stock pipe with the muffler removed and it sounded real good

 

So you installed the y-pipe for dual outlets? Side or out the back?

 

out the back