03 5.4 fx4. The factory y pipe has 1 1/2 inch restrictors in it. Why? Who has done the y pipe modification and what were your results? What are the positives and negatives of the high flow modification?

 

I modded the stock pipe in my '05 Excursion 6.8L. Front what i know the restricted flow warms up the motor faster. Once I removed and repace the restricted spot I had significant difference in bottom end power. I wish I could tell you more. My current exhaust is single into Flowmaster dual out. I didn't want my truck sounding like an Audi or something. The current setup is just enough growl to give her character but not crazy to wake my neighbors.