Hey staceyq!
On my side, I got the CPE 3"Catted DP so the heatshield wasn't even fitting on so I just leaved it without it. As of now I didn't have any heat issue. (that's including a complete day of drag racing!!)
But I'm located in Quebec, Canada where temp are not very hot in summer (22? to 25? celsius degree in average).
+3? to +5? celsius degre more than ambient temp Charge air temp most of time (with Injen CAI & MTC FMIC) going up to +8? to +10? celsius degree more than ambient temp when stopping on a long redlight or when waiting in row for drag race.
If you can do one heatshield I suggest you to go for it but IMO if you don't no worries you should be ok without it.
-Seb- -