I've been researching the various parts and installation. today I was speaking with someone about installation and in passing he mentioned that he has fabricated systems. I didn't go over price. my questions are thus. Is there a purpose for the X or H pipe or can you go directly from downpipe to muffler? Is there reason not to use my stock muffler if he can remove the existing pipe and weld a 3" pipe? Would he need to do the same with the tail pipe. I would use a 4 hole 3" downpipe. thanks