I have a 02 F-250 5.4 Auto. I currently have custom dual exhaust on it which consists of a Y pipe after the cat and no muffler. I've been doing a lot of searching on here and it seems that a few of the 5.4 guys and a bunch of V10 guys have the "eBay Y Pipe" mod. to take the restriction out of the horrible factory "T" Also a few of them have taken out the cat.

I'm looking to fabricate my own Y-pipe out of the manifolds and maybe taking out the cat, (if so, my truck will be off road only ) Are there any downsides to cutting this much backpressure out? I don't rod the heck out of things, but do like loud pipes. This is a daily driver truck and has 107k miles on it. Do I need to worry about messing up the engine to bad from straight pipes? Thanks guys!
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Nobody? I'll put this in the V10 forum too...