I did some more digging, and I'm not 100% sold that the 2000-2001 Y-pipe is as bad as gets commonly tossed about.

The y pipe is indeed a full 3" exit. Just before and after the cat and the muffler, dodge used 2.5" reducers to attach to the cat and muffler. The rest of the system is all 3". Why they did this is beyond me, save that perhaps they had extra stock of 2.5" si/so catalytic converters and mufflers lying around. Cutting those reducers out and running 3" si/so cat and muffler really woke mine up.

All that Jegs, pacestter, and magnaflow y pipe stuff is 2.5" out, which is why you don't see the 2000-2001 years listed. I could definitely see where going 2" dual down pipes to 2.5" out is a major restriction. 2x 2" down pipes into a 3" out Y-pipe isn't nearly as bad. I think you boys with older trucks got the shaft from the factory, and if I'm not mistaken, the 2000-2001 rams were both rated at 15hp better than their earlier counterparts.

Wonder what they would have rated them had they used all 3" pipe, cats, and mufflers?

 

So it sounds like im just going to keep my stock y pipe and gut the cat