Figured I'd ask this question here as I feel this forum has one of the best knowledge base around. I have an 03 crown vic that has a m112. My engine recently let go and I now have a forged 5.4 that I will be replacing it with. I will be putting trick flow heads on the 5.4 and I plan on increasing boost. I'm running into header issues. No one makes headers for a 5.4 swapped crown vic (no surprise) but stainless works does make a set for the 4.6. I believe with some cutting and welding I'll be able to get them to fit but I really don't want to hack up 1000 dollar headers if I don't have to. The other option I'm considering is modifying some shorty headers. Cut off the little 2.5in collector and replacing it with a 3in. I'd rather hack up some 300 dollar shorties but I know that the big advantage of long tubes are how well they scavenge. Will shorties with the modified collectors flow enough or will I lose to much low end due to them flowing to much at low speeds and not being able to scavenge like long tubes?
