Joe_Schmo11

I bought a set of longtubes for my 99 gt and have recently gotten a 99 5.4 bottom end. I Have a set of Romeo PI heads Off a 03 gt that I plan on putting on the 5.4. My question is will I be able to use the longtubes I originally bought for my 4.6 on the 5.4?

school boy

I have heard long tubes wont fit the 5.4 in the mustang, it raises the header too high and the collectors hit. But after all, you got them so try them when the 5.4 is installed.