So yeah, I am a truck owner and when I decided to put 8 inch stacks on my Peterbilt, off came the old 5 inch stacks. Had been wanting to put them as a dual system on my excursion somehow, but having the fuel tank in the way in the back and stuff put off doing it for a long time. But today I finally decided to give it a go.
Cut my MBRP 4 inch exhaust off right at the rear of the transmission, used the 4 to 5 inch chrome tip to step the size up. Worked pretty good. Not sure how long it will hold up, but I think it should do fine. From there attached the old peterbilt Y pipe and was able to just go straight from there out the passengers side with the old 5 inch truck stack, and on the drivers side had to use about a 2 foot section of 5 inch flex pipe to make the turn and span the gap to get the drivers side pipe to come out at the same spot and same angle as the passengers side. Then used the old stack mounts from my truck to mount the stacks to the rear running board bracket. Only problem is, because of the design of the Y pipe and the longer trip over to the drivers side, the exhaust favors the passenger side so I get more smoke on that side. I can fix that though if I want later. But for now I love it!
I think it turned out really cool. And sounds cool as hell. I finally have that awesome turbo whistle I was wanting so bad. Little noisier Excursion, but it really isn't too noisy.
So here is some video I got of it when I was done.
YouTube - 5 inch truck stacks on a 2000 Ford Excursion Not Vertical:-)