Which downpipe?
 

I've owned my FD for 3 years now and I just got it running. I wish to upgrade a bit and have my apexi intakes as far as inlet...my HFC and CB as far as outlet. Which downpipe would be recommended? I have a 3" Random hfc and Fujitsubu cat back. Does it drop engine temperature by a lot? What heat wrap did u guys use? Air pump should be gone? What all do I need for this? Any help in slight upgrades appreciated.