Can anyone direct me to a good company that supplies upgraded ECU's? Thanks!

For what gen rx7?
Honestly there are only a couple out there that are worth looking into for the FC, but IMO i woudl rather fo piggy back than tune the ECU, cause once the ECU is changed it cant be changed back by setting a switch to default :P

It's actually for an NA FC ('86) with HKS intake, Racing Beat header, no cat, and APEX'i N1 exhaust... I thought about an APEX'i SAFC-II also but I'm also looking at getting rid of all the limiters too. What do you think of the Corksport ECU?

i would say the RE Amemiya REDOM ecu, but those are A) rare and B) for turbo cars