Dynomax welded vs X

a while back I saw a thread on muffler flow rates and decible levels and think i found the same one when I was searching but what I couldnt find was the difference in the welded and X offerings from Dynomax.

My set up is a headders off a 360, planning to run an X pipe (you want it as close to the headders as possible right?) and bring the exhaust out the rear. I figure a 2.5" size will do me fine. I like quiet and efficiency so from the graphs and reviews Ive seen, Dynomax is the ticket for me.

So who can tell me the difference before I order? Thanks!

-Sefus