Install an aluminum heat shield between exhaust and tub. You can mount it directly to the hat sections, but it will work better and collect less debris with a little stand-off if you have the clearence. I just used 1/16" 5052 aluminum and rolled the edges a little for some rigidity.
As for the cross over pipe, I ran one on my 3B for 20 something years and they do mellow the exhaust somewhat. I used 2 1/4" pipe with a downward canted "nipple" welded into the header collector immediatly in front of the flange and routed the removable U shaped cross over pipe in front of the cross member and above the skid plate. It made greasing the front drive shaft a pain in the butt and was not re-installed when I replaced the headers (Hookers). Worthwhile? Probably not.
1955 CJ 3B, 381cid sbc (441cid all aluminum sbc coming soon), AGE M22W, Teralows, Warn OD, OBA, Premier Power welder, Warn 8274
1968 CJ 5, factory 225" w/ headers/450 cfm Holley, T86AA, Belleview winch, Warn OD
2012 Wrangler Rubicon Unlimited, Warn 9.5 xp-s winch