Having had 2 home made exhaust systems rust off my 83 F150, i always swear the next one will be welded up in stainless steel. Just having to fab up something quick before winter, i thought i would play around with some sound management ideas... I had a long section of 4 inch pipe i found at the scrap when i was unloading my junk. I have no idea what it came from, but it is as thick as good heavy exhaust pipe... My 300 six has an EFI Head that has been pocket ported, a mild Elgin Camshaft. Offenhauser Dual port, 390 Holley carb. Dual Exhaust manifolds, with 4 foot 2 inch pipes. I cut the old crap off, and welded this 4 inch pipe on. It goes all the way back to the bumper. I welded a cap on the end, and cut a 2x 3 inch hole a foot or so from the end. I am happy with how loud it really is not, with no muffler. To be honest, i kind of enjoy the Hillbilly pipe for now. I might add a 4 inch resonator i have off a Diesel Truck later, put it inline under the Cab... What i am kind shocked with is, it seems i have picked up some power over my 3 inch muffled system of before. I know this all goes against all rules of street going Exhaust pipe sizing. What i come up with is, the tune of my Engine and that it can breathe some. Also i think the 4 foot 2 inch pipes going into this Sewer pipe help... Exhaust expansion and sound wave management was my play here, also on the quick and cheap... Something to think about, like we need more of that.