I have been doing research on exhaust headers for my track car project. I have narrowed down my choice to the Killer Bee system based on my performance targets, discussions with tuners that have done back to back runs and owners that have installed the system with positive results.
I know there are Killer Bee Headers installed on EJ20 engines out there but have yet to talk to someone that has the header or found before and after dyno results on the 2.0L engine. So far all the test results I have seen have been 2.5 engines.
Test results will be the same. It can be argued that the collector on the KB one creates a lot of excessive heat in that one spot, but it's still superior to alternatives in durability. Another option is Full-Race, but be aware the price tag is a bit more.